In the bowl of a stand mixer fitted with a paddle attachment, cream butter on medium high speed until light and fluffy. Add sugar and continue to beat until smooth. Add egg and vanilla extract and beat on low speed until well blended.
In a large bowl, whisk together flour, baking powder and salt. With mixer on low speed, slowly add flour mixture to butter mixture until well blended.
Divide dough into three equal portions and place in three different bowls. Keep one portion plain. Add the cooled, melted chocolate to the second portion until evenly combined.
Add the freeze dried strawberries to a small sandwich bag. Use a rolling pin to crush the berries into a fine powder. You can also use the bottom of a frying pan. Mixture should amount to about two tablespoons. Add to the third portion of dough along with a bit of gel food coloring until well combined. Start off with a small amount of gel food coloring and go from there until you reach desired color.
Line a 9x5 loaf pan with wax paper overlapping edges. Press the vanilla dough into the bottom of the pan until flat and even. Top with pink dough, pressing until smooth and even. Top with the chocolate dough. Top with more wax paper and press down on all layers. Refrigerate overnight.
Preheat oven to 350 degrees. Line a large baking sheet with parchment paper. Lift the dough out of the loaf pan onto a flat surface. Cut the dough in half lengthwise to make two equal portions. Cut each portion crosswise into 1/4 inch slices. Place slices on prepared sheet 2 inches apart. (cookies will spread) Put remaining dough in fridge to stay cold while cookies are baking. Bake cookies for 13-15 minutes until just lightly browned. Cool on sheet for 5 minutes before removing to wire rack to cool completely. Repeat with remaining dough.