1/2 Cup canned almond paste coarsely crumbled
1/2 tsp salt
3/4 Cup sugar divided
2 sticks unsalted butter softened
1 egg separated
1 tsp almond extract
1 1/4 Cups all-purpose flour
1/2 Cup sliced almonds (approx. 1 1/2 ounces)
- Pulse almond paste in a food processor until broken up into small bits, then add salt and 1/4 cup sugar and continue to pulse until finely ground, about 1 minute.
- Put oven rack in middle position and preheat oven to 350°F. Butter a 9-inch square baking pan, then line with foil, leaving a 2-inch overhang on 2 opposite sides, and butter foil.
- Beat together butter and remaining 1/2 cup sugar in a large bowl with an electric mixer at medium-high speed until pale and fluffy, about 3 minutes in a stand mixer (preferably fitted with a paddle attachment) or 6 minutes with a handheld. Add almond mixture, egg yolk, and almond extract and beat until combined well, about 2 minutes. Reduce speed to low, then add flour and mix until combined. Spread batter evenly in pan with an offset spatula. Lightly beat egg white in a small bowl, then brush some of it over batter and sprinkle evenly with almonds.
- Bake until top is golden, 35 to 40 minutes. Cool completely in pan on a rack, about 1 hour. Transfer with foil to a cutting board, then discard foil. Cut into squares or rounds.
Cookies keep, layered between sheets of wax paper or parchment, in an airtight container at room temperature 4 days. They WILL go stale faster than other Christmas cookies!