Preheat oven to 350°F (180°C). Spray 3 (8-inch) round cake pans with baking spray with flour. Line bottom of pans with parchment paper.

In the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugar at medium speed until fluffy, 3 to 4 minutes, stopping to scrape sides of bowl. Add eggs and egg whites, one at a time, beating well after each addition.

In a medium bowl, whisk together flour, ground pistachios, salt, and baking powder. In a small bowl, whisk together buttermilk, extracts, and food coloring (if using). With mixer on low speed, gradually add flour mixture to butter mixture alternately with buttermilk mixture, beginning and ending with flour mixture, beating just until combined after each addition. Divide batter among prepared pans (about 519 grams each), and spread smooth with a small offset spatula.

Bake until a wooden pick inserted in center comes out clean, about 30 minutes. Let cool in pans for 10 minutes. Remove from pans, and let cool completely on wire racks.

Spread a thin layer of Roasted Strawberry Swiss Meringue Buttercream on 1 cooled cake layer (about ¼ cup or 42 grams). Place 2 cups buttercream in a pastry bag fitted with a medium round piping tip. Pipe a ½-inch-thick border of buttercream around edge of cake layer. Spread half of Roasted Strawberry Jam within border. Top with second cake layer. Spread a thin layer of buttercream on cake layer; pipe a ½-inch-thick border of buttercream around edge of cake layer. Spread remaining Roasted Strawberry Jam within border. Top with remaining cake layer. Spread a thin layer of buttercream on top and sides of cake. Freeze for30 minutes.

Spread remaining Roasted Strawberry Swiss Meringue Buttercream on top and sides of cake. Garnish with strawberries and chopped pistachios, if desired. Refrigerate in an airtight container for up to 3 days.