Spray a 12-cup muffin tin with nonstick spray and set aside.
Place the warm milk, sugar, yeast, flour, egg yolks and salt in the bowl of a stand mixer fitted with the paddle attachment. Combine on low speed for about 1 minute. Change the paddle to dough hook and rest the dough for 15 minutes.
Add 4 Tbsp. of butter (warmed to room temperature) and mix on low speed. Increase the speed to medium and mix until the dough pulls away from the sides of the bowl and you are able to gently pull the dough into a thin sheet that light will pass through; about 8 minutes more of mixing.
Turn the dough out onto a lightly floured work surface and using your hands roll and shape to form a large ball. Liberally butter a separate bowl and place the dough into the bowl rolling it around so all surfaces get buttered. Cover and set aside in a warm, dry place until doubled in size; about 1 hour.
Remove the dough from the bowl and roll into a 12 x 12 inch square; about 1/2 inch thick. Melt the remaining tablespoon of butter and brush onto the top of the dough.
Use a pizza cutter to cut the dough into 12 (12 x 1 inch) strips. Stack the strips into 2 stacks of 6 strips each. Lay the stacks on their sides and cut each stack into 6 (2 inch) wide pieces. Lay each piece on its side into the cups of the prepared muffin tin. Cover and set aside to rise again in a warm, dry place until doubled in size; 30 to 40 minutes.
Preheat the oven to 400 degrees. Remove the cover and place the rolls in to bake for 8 to 10 minutes until tops are golden brown. Internal temperature should be 200 degrees if you choose to measure. Rotate the pan halfway through cook time.
Remove the muffin tin to a cooling rack and cool for 2 to 3 minutes before serving.