Rainbow Cookies Recipe

Prepare

Preheat the oven to 350°F (175°C). Line two 9x13-inch rimmed baking sheets (or two 9x9-inch square pans) with parchment paper, leaving extra paper over the edges to lift the layers later. Lightly grease the parchment.

Cream butter and sugar

In a large bowl or stand mixer fitted with the paddle attachment, beat the softened butter and granulated sugar on medium-high speed until light and fluffy, about 3–4 minutes.

Add eggs and extracts

Add eggs one at a time, beating well after each addition. Mix in the vanilla and almond extracts until incorporated.

Combine dry ingredients

In a separate bowl, whisk together the all-purpose flour, baking powder, and salt.

Alternate dry and wet

With the mixer on low speed, add about one-third of the flour mixture to the butter mixture, then add one tablespoon of milk. Continue alternating, ending with the flour, and mix just until combined; do not overmix. The batter will be slightly thick.

Divide and color batter

Divide the batter evenly into six small bowls (about 1/3 cup each if using two 9x13 sheets, or adjust for pan size). Tint each bowl with one of the food colorings: red, orange, yellow, green, blue, purple. Stir until color is uniform.

Spread layers

Working one color at a time, spread each colored batter into a very thin even layer (about 1/8 to 1/4 inch thick) on the prepared parchment using an offset spatula. If using two sheets, plan three layers per sheet. Smooth the surface; thin layers bake quickly, so keep thickness consistent.

Bake

Bake the thin colored layers for 6–9 minutes, or until the edges are set and the top is just barely springy — do not overbake or they will dry out. Rotate pans halfway through baking for even color.

Cool and remove

Allow the layers to cool completely on a wire rack for 10–15 minutes. Once warm and set, use the parchment paper to gently lift each layer onto a flat surface. If any layers have curled edges, trim to even them.

Lightly warm the apricot jam in a small saucepan or microwave for 10–15 seconds and strain if necessary to remove pieces, creating a smooth spreadable glaze. This thins the jam and makes it easier to spread between layers.

Place the chopped chocolate in a heatproof bowl. In a small saucepan, heat the heavy cream until it just begins to simmer (small bubbles around the edge). Pour the hot cream over the chocolate and let sit 1 minute, then whisk until smooth and glossy. Stir in the tablespoon of butter if using for extra shine. Allow ganache to cool and thicken slightly so it is spreadable but still pourable.

Stack the layers: place the purple layer (or one color) on your work surface, spread a thin, even layer (about 1 teaspoon) of warmed apricot jam over it. Place the blue layer on top, lightly press to adhere, then spread jam. Continue stacking in order (purple, blue, green, yellow, orange, red) or reverse to create a mirrored effect, adding jam between each. Use a small offset spatula to keep layers even.

Trim and chill: once stacked, gently press the stack together and trim the edges with a sharp knife to make straight sides if desired. Wrap the stack in plastic wrap and chill in the refrigerator for at least 30 minutes to firm up for easier slicing.

Coat with ganache: place wire rack over a sheet pan. Pour the slightly cooled ganache over the chilled layered stack, using an offset spatula to spread and ensure the top and sides are covered evenly. Let excess drip off. Return to fridge for 10–15 minutes to set the ganache.

Slice and finish: using a sharp serrated knife warmed under hot water and wiped dry between cuts, slice the chilled cake into rectangular cookies about 2 x 1 inches (or 1 x 2 cm thick slices) pressing cleanly. Dust lightly with powdered sugar on the cut sides if desired and serve chilled or at room temperature.