Make the topping
In a food processor, pulse the almonds with the flour, baking soda and salt until the almonds are coarsely ground. In the bowl of a stand mixer fitted with the paddle, cream the butter with both sugars until fluffy, about 3 minutes. Scrape down the side of the bowl. Add the egg yolk and vanilla and beat at medium-high speed for 2 minutes. Scrape down the bowl again. Add the almond-flour mixture all at once and mix at low speed just until incorporated.