Adjust an oven rack to the middle position and preheat the oven to 350F [180C]. Line three baking sheets with parchment paper.

In a medium bowl, combine the flour, baking soda, and salt.

In a food processor, pulverize the strawberries into a powder.

In a stand mixer, beat the butter on medium speed until creamy, about 1 minute. Add the sugar and beat until light and fluffy, 2 to 3 minutes. Add the egg, yolk, and vanilla, and beat until combined. Add the flour mixture and beat on low speed until just combined.

Dump the dough onto a work surface and divide it into three equal portions.

Add one-third of the dough back into the mixer and mix in the powdered strawberries and food coloring, if using, on low speed until combined. Remove the dough and set aside.

Add another third of the dough to the mixer, mix in the cocoa powder on low speed until combined.

Pinch a small portion (about 1/2 oz [15 g]) of each of the three doughs, press them gently together. Press the piece into a cookie scoop or roll it into a ball, then roll the ball in sprinkles or granulated sugar.

Place 6 or 7 cookies on each sheet pan. Bake the cookies one pan at a time, rotating halfway through baking, until the sides are set and the cookies are puffed, about 10 to 11 minutes.

Transfer the sheet pan to a wire rack and let the cookies cool for 5 to 10 minutes on the pan, then remove them to cool completely on the wire rack.