1. Place racks in top and lower thirds of oven and preheat to 350°F. Place almonds on a baking sheet on lower rack and toast until fragrant, 8 to 10 minutes, shaking pan a few times. Transfer to a bowl to cool to room temperature. Turn oven off.
2. Place 1/4 cup almonds in food processor and process until finely ground; transfer to a small bowl. Coarsely chop remaining nuts and place in a separate small bowl.
3. Place butter, sugar and almond extract in same food processor (no need to rinse) and blend until light, about 2 minutes, scraping down sides halfway through. Add flour, salt and ground almonds and pulse until just combined. Divide dough into 2 portions. Pat into 2 6-inch flat squares, roughly 3/8-inch thick. Wrap in plastic and refrigerate for at least 1 hour or until firm.
4. Preheat oven to 300°F. Line 2 large, rimmed baking sheets with parchment. Let dough rest at room temperature until pliable enough to roll. Roll out a square of dough between 2 sheets of lightly floured waxed paper to 1/8-inch thickness. Use a sharp knife to cut dough into 2-inch squares. Transfer to baking sheets, leaving about 1/2 inch between each. Repeat with remaining dough. Combine scraps, reroll once and cut. If dough becomes too soft to roll, refrigerate briefly.
5. Bake cookies until light golden, 35 to 40 minutes. Let stand for 5 minutes on baking sheets on wire racks, then transfer cookies to racks to cool completely. When cookies are cool, set up 2 baking sheets lined with parchment. Put 1/2 of chocolate in a microwave-safe bowl and microwave on high for 30 seconds; stir. Continue to heat and stir in 15-second increments until chocolate has melted. Add remaining chocolate and allow it to sit at room temperature, stirring occasionally, until completely smooth. Dip 1/2 of each cookie in chocolate. Sprinkle with reserved chopped almonds and place on baking sheets to set.