How to Make It
In the bowl of a stand mixer fitted with paddle (or by hand), mix the eggs, egg yolk, and sugar on medium-high until consistent and pale yellow. Add the vanilla and mix until incorporated.
Make one batch of the basic dough, fry, and let cool.
Start by making the crumbs. In a medium-sized bowl, combine the brown sugar, powdered sugar, flour, cinnamon, salt, and vanilla, stirring to combine, making sure to break up any chunks of brown sugar. In three additions, drizzle the melted butter over the sugar-flour mixture, mixing until all the butter has been absorbed and you see little kibble-like balls start to form. If some balls get too big, break them up with your fingers, and continue to stir.