Bring a small saucepan of water to a boil. Add 36 almonds to the pan. Cook until the skins loosen, 20 to 30 seconds. Drain, let cool, then slip the skins off the almonds. Pat the blanched almonds dry.
In a food processor, pulse the remaining almonds and 1/4 cup sugar until the mixture looks like wet sand. In a small bowl, whisk the flour, baking soda and salt.
In a large bowl using an electric mixer, beat the butter on medium-high until smooth, about 1 minute. Add the remaining 1/2 cup sugar; beat until fluffy, about 2 minutes. Add 1 whole egg and almond extract; beat until smooth, about 2 minutes.
Using a wooden spoon, stir the flour mixture and almond mixture into the butter mixture until blended. Cover and chill the dough until firm enough to roll into balls, about 30 minutes.
Position racks in the upper and lower thirds of the oven; preheat to 350 degrees . Line 2 rimmed baking sheets with parchment. Roll 1-inch pieces of dough into balls. Divide between prepared baking sheets, spacing 2 inches apart. Using your thumb, make a divot in the center of each cookie. In a small bowl, lightly beat the egg yolk with a few drops water; brush the egg wash over each cookie. Place 1 blanched almond in each divot.
Bake the cookies, swapping the sheets halfway through baking, until golden brown, 15 to 17 minutes. Let the cookies cool on the sheet 5 minutes, then transfer, on the parchment, to racks to cool completely.