Step 1
Preheat oven to 300 degrees F (150 degrees C). Line bottom and sides of an 8-inch square baking pan with parchment paper; crease corners well.
Step 2
Whisk together 1 cup flour and 2 tablespoons confectioners' sugar; cut in 1/2 cup butter until mixture resembles fine crumbs. Pat mixture evenly into prepared pan.
Step 3
Bake in the preheated oven for 20 minutes; remove to cool on a wire rack about 15 minutes. Top base evenly with raspberry jam.
Step 4
Preheat oven to 375 degrees F (190 degrees C).
Step 5
Beat white sugar and 1/2 cup butter together until fluffy; beat in eggs until fluffy and pale yellow. Beat rice flour into egg mixture until well combined; stir in food coloring until batter reaches desired shade of red. Spread batter evenly over jam layer.
Step 6
Bake in the preheated oven until a toothpick inserted into the center comes out clean about 30 minutes. Cool completely in the pan; about 20 minutes.
Step 7
Beat 2 cups confectioners' sugar and 1/3 cup butter together in a bowl with an electric mixer until smooth; stir in milk and maple extract. Spread icing evenly over cooled bars.
Step 8
Hold edges of parchment paper; lift squares out of pan to a cutting board. Slice into 1-inch squares with a very sharp knife.