Preparation Pulse almonds in a food processor until coarsely ground, then add sugar and pulse until almonds are finely ground. Transfer to a large bowl. Add almond extract, food coloring, banana, and egg white and mix with an electric mixer at low speed until a sticky, heavy paste forms. Spoon into pastry bag. Line 2 baking sheets with parchment paper and lightly butter. Pipe 3- by 3/4-inch strips of dough onto paper about 1/2 inch apart. Chill, uncovered, overnight (8 to 12 hours). Preheat oven to 300°F. Bake cookies in upper and lower thirds of oven, switching position of sheets halfway through baking, 20 minutes total. Cool on sheets on racks 10 minutes, then bake 15 minutes more. Cool completely on sheets on racks. Peel cookies from paper.
Preparation Pulse almonds in a food processor until coarsely ground, then add sugar and pulse until almonds are finely ground. Transfer to a large bowl. Add almond extract, food coloring, banana, and egg white and mix with an electric mixer at low speed until a sticky, heavy paste forms. Spoon into pastry bag. Line 2 baking sheets with parchment paper and lightly butter. Pipe 3- by 3/4-inch strips of dough onto paper about 1/2 inch apart. Chill, uncovered, overnight (8 to 12 hours). Preheat oven to 300°F. Bake cookies in upper and lower thirds of oven, switching position of sheets halfway through baking, 20 minutes total. Cool on sheets on racks 10 minutes, then bake 15 minutes more. Cool completely on sheets on racks. Peel cookies from paper.