Funfetti Cake: Which Sprinkles to Use So They Don't Bleed Colour

For funfetti cake batter, go with rainbow jimmies (the long sugar sprinkles). Flat confetti sprinkles made from pressed sugar work well too. Save round sprinkles, metallic pearls, and mixed sprinkle blends for the topping. Here's a quick rundown:

• Jimmies (rainbow sprinkles): the best choice. They hold their colour, so when you slice the cake you get clean, colourful little dashes.

• Confetti sprinkles (sequins, hearts, stars): work in most cases. They're bigger and firmer, so they show up as bold "dots" in the slice.

• Round sprinkles (nonpareils): don't put these in the batter. They bleed colour the moment they touch damp batter.

• Sugar pearls and metallic balls: keep these out of the batter too. They lose their shine and stay hard as little pebbles.

• Chocolate sprinkles (vermicelli): they won't bleed colour, but they'll melt, leaving you with a "stracciatella" effect rather than true funfetti.

We stock Happy Sprinkles Rainbow Jimmies for this. You'll find the full range, including decorating mixes, under sugar sprinkles. With mixes that include round or shaped pieces, remember they're meant for the frosting, not the batter.

Round sprinkles bleed colour because their colouring sits in just a thin layer on the surface of the sugar, and damp batter dissolves that layer within seconds of mixing. Both the sugar and the dye dissolve in water. Round sprinkles are also tiny, so they have a lot of surface area relative to their weight — and therefore a lot of colour they can release.

Jimmies are made differently. Besides sugar, they usually contain starch and fat, and they're coated in a thin glossy layer (wax or shellac). That coating likely slows down the colour release enough that the batter has time to set in the oven before the colour can spread. That's why bakers, including Sally's Baking Addiction, recommend using jimmies in the batter and saving round sprinkles for decoration only. Jimmies from different brands behave differently in the oven, so it's worth doing the teaspoon-of-water test described below.

The practical rule that follows: the longer sprinkles sit in wet batter, and the more you mix them in, the more colour they'll release — no matter what kind of sprinkle it is. Even jimmies will tint the batter if they spend ten minutes in the mixer.

For batter made with about 300 g (10.5 oz) of flour (enough for a 20–22 cm/8–9 in cake, two to three layers), use 70–90 g (2.5–3.2 oz) of rainbow jimmies. That works out to roughly 25–30% of the flour's weight.

• Less (40–50 g / 1.4–1.8 oz): subtle flecks, and the cake reads more like plain vanilla.

• 70–90 g (2.5–3.2 oz): the classic funfetti look, with colour in every bite.

• More than 120 g (4.2 oz): the batter gets heavy, sprinkles sink to the bottom, and the cake turns dense and gummy in spots.

12 cupcakes only need 40–50 g (1.4–1.8 oz). Save a small handful to sprinkle on top so it's obvious what's inside.

Fold the sprinkles in right at the very end, with a spatula, using just 6–8 strokes, and get the batter into the oven straight away. Here's the step-by-step method:

1. Have your oven and tins ready beforehand. No more than 2–3 minutes should pass between folding in the sprinkles and baking.

2. Transfer the finished batter from the mixer to a bowl. Never mix sprinkles in with a whisk or dough hook.

3. You can toss the sprinkles in flour first. One tablespoon of flour from the recipe is enough for 80 g (2.8 oz) of jimmies. This stops them clumping together and keeps them from sinking as much in thinner batter.

4. Add them in and fold with a spatula, scooping from the bottom up, 6–8 strokes. The batter doesn't need to look perfectly even — the sprinkles will distribute themselves as the cake bakes.

5. Divide the batter between the tins, smooth it out, and bake right away. Don't let batter with sprinkles folded in sit on the counter while another layer finishes baking. If you're baking layers one at a time, split the batter in half and fold the sprinkles into each half just before it goes in the oven.

If you spot colourful "tails" trailing off the jimmies in the bowl, you've either mixed too long or the batter is too warm and thin.

Funfetti needs a pale, fairly thick vanilla batter. Against a white background the sprinkles really pop, and a thick batter keeps them evenly suspended.

• Colour: the palest cake comes from using just egg whites, or a mix of whites and whole eggs. On a chocolate batter, the flecks barely show. If you want a white cake, skip the brown sugar and dark vanilla extract.

• Thickness: the batter should drop off the spatula in slow dollops, not pour. In a thinner batter (like a sponge, or one with a lot of milk or oil), the sprinkles will sink and leave a colourful "sole" at the bottom of the layer.

• Temperature: keep butter, eggs, and milk at room temperature, but don't let the batter get too warm. The warmer it is, the faster it dissolves the sugar coating.

• Flavour: funfetti is essentially a vanilla cake. For how much vanilla to use and in what form, see our article How Much Vanilla to Use in Cookies, Frosting, and Christmas Bread.

A whisked-egg sponge isn't ideal for funfetti — the sprinkles sink, and folding them in would deflate the foam. If you'd like a ready-made recipe for a fun, colourful kids' cake, check out our rainbow kids' cake.

Try the teaspoon-of-water test: drop a few sprinkles into it and wait 2 minutes.

• If the water stays mostly clear after 2 minutes and the sprinkles hold their shape: you can use them in the batter.

• If the water turns colourful within those 2 minutes and the sprinkles start dissolving: keep them for the top, the frosting, or the icing only.

The test is much quicker than mixing and baking, but it gives you a good indication of how the sprinkles will behave in moisture. It's especially handy for unlabelled sprinkles, like ones from a mixed set or a gift pack. Naturally coloured sprinkles (made with beetroot, turmeric, or spirulina) tend to be more sensitive to heat. Their colours can turn dull or fade in the oven, even if they don't actually bleed.

Top it with white buttercream or cream cheese frosting, adding sprinkles only after frosting. At this stage you can use anything, including round sprinkles, pearls, and shaped mixes like Happy Sprinkles Queen of the Dancefloor.

• Frosting: the whiter it is, the more the sprinkles will stand out. For tips on whitening frosting, see our article Snow-White Buttercream.

• Timing: round sprinkles and nonpareils will bleed colour into frosting too, usually within a few hours in the fridge. If you're making the cake a day ahead, add them just before serving. Jimmies and confetti sprinkles can go on straight away.

• Technique: press sprinkles onto the sides of the cake with your palm or a flat spatula while the frosting is still fresh and tacky. Sprinkle the top from a height of 20–30 cm (8–12 in) so they spread out evenly.

For more techniques, from edging a cake with jimmies to creating ombre effects, see our article How to Decorate a Cake with Sprinkles. If you want to colour the layers themselves, take a look at our rainbow cake.