In another bowl, cream butter and sugar until lightened. Add eggs, egg yolks, yogurt, vanilla, and pumpkin puree. Mix until well combined.
3 tablespoons unsalted butter, 1 egg, 2 egg yolks, 1/2 cup plain yogurt, 1 teaspoon vanilla, 1 cup sugar, 1 cup pumpkin puree
Add dry ingredients to wet, then gently stir until just combined.
On a well-floured surface, roll dollops of dough into 1/2 inch round snakes. Cut small bits of dough.
Add 8-10 bits of dough to the oil at a time. Cook on one side for about a minute, then flip them over using a spider or a chopstick. Cook for another 45 or so seconds on the other side, then drain on a plate lined with paper towels.
While donuts are still hot but cool enough to handle, roll in cinnamon sugar mixture.