Beat butter at medium speed with an electric mixer until fluffy and creamy. Gradually add sugar, beating until well blended. Add egg whites, 1 at a time, beating until blended after each addition. Add extracts; beat well.
Combine flour, baking powder, and salt; add to butter mixture alternately with 1 cup coconut milk, beginning and ending with flour mixture. Beat at low speed until blended after each addition.
Divide batter evenly among 18 paper-lined cups of muffin pans. Bake at 350° for 20 to 23 minutes or until batter is set but centers of cupcakes still look slightly wet. (Do not overcook.) Cool in pans 10 minutes; transfer to wire racks.
Combine amaretto liqueur and remaining 3 tablespoons coconut milk; stir well. Spoon mixture evenly over tops of warm cupcakes, spreading with back of spoon. Cool completely.
Frost cupcakes with Coconut-Cream Cheese Frosting, and sprinkle with toasted coconut. Store at room temperature.