Preheat oven to 350 degrees. In a mixing bowl, whisk together flour, cornstarch, baking powder, 3/4 tsp cinnamon, nutmeg and salt, set aside. In the bowl of an electric stand mixer, whip together butter, 3/4 cup granulated sugar and light brown sugar until pale and fluffy, about 4-5 minutes. Mix in egg and egg yolk. Stir in sour cream, vanilla and almond extract. Add in dry mixture and mix just until combine. Allow mixture to rest 20 minutes at room temperature. In a separate small bowl, combine 1/4 cup granulated sugar with 1 1/4 tsp cinnamon. Scoop dough out by the heaping tablespoonfuls (each ball should be about 1 1/2 Tbsp) and roll into balls, then roll balls in cinnamon sugar mixture (give them a good coating). Bake on Silpat lined or buttered cookie sheets in preheated oven for 10-12 minutes. Allow to cool several minutes before transferring to wire rack to cool. Store in an airtight container.