Warm the milk by placing it in a bowl in the microwave for 20-30 seconds, or until warm to the touch (but not boiling).
Pour the warmed milk into a large mixing bowl (or electric stand mixer bowl) and add the yeast and 1 tablespoon sugar. Lightly stir together with a fork or whisk and let sit for 5-8 minutes until foamy. If the mixture doesn’t become foamy after 10 minutes, discard and make a new batch of milk-sugar-yeast mixture.
With the whisk attachment (or handheld whisk) mix in the eggs, egg yolks, remaining sugar, melted butter, and vanilla extract just until combined.
Mix in the flour, salt, and cinnamon until a tacky-sticky dough forms.
Sprinkle flour on your counter. Knead the dough on the counter until smooth, adding up to 2-3 tbsp extra flour if the dough is too sticky.
Grease a large bowl with some oil or cooking spray. Transfer the smooth ball of dough to the bowl and cover with plastic wrap or a towel. Let rise at room temperature in a warm/room temperature place for about 1 to 1 1/2 hours or until the dough has doubled in size.
****While the donuts rise, prepare the Bavarian cream, recipe below!***
Prepare 2 baking pans and line with cut squares of parchment paper.
Once the dough has risen, transfer the dough, punch it down and transfer to a floured work surface. Roll until it’s about 3/4” thick.
Use a round cookie cutter about 2 1/2 to 3 inches in diameter (or top of a glass cup) and cut out donut rounds. Place the cut-outs onto the prepared parchment squares on the baking sheet.
Re-roll any dough scraps and cut out more donut rounds.
Lightly cover each donut-dough pan with a kitchen towel and set aside to rise for 1 hour.