Dough: Sprinkle yeast over water and milk. Add 1 tablespoon sugar and stir to combine. Let sit for 5-7 minutes to allow mixture to bubble and active.
In the bowl of a stand mixer, whisk together yeast mixture, remaining sugar, egg, and egg yolk. Whisk salt into flour. Add 2 cups of flour to mixing bowl. Use the dough hook attachment to mix together. Add another 1 cup of flour. Continue to knead on low speed, add softened butter 1 tablespoon at a time. Add remaining cup of flour and knead until the dough is smooth and cleans the sides of the bowl. Add confetti sprinkles and mix until evenly distributed in the dough.
Transfer dough to a lightly greased bowl. Cover with plastic wrap and let dough rest at room temperature for about an hour until double has doubled in volume.
Punch down risen dough. Transfer to a lightly floured working surface. Roll dough into a 20 x 14-inch rectangle. Spread 1/3 cup softened butter over dough.
Cinnamon Sugar Filling: In a bowl, mix together sugar, brown sugar, and cinnamon. Distribute cinnamon sugar filling and gently press into dough. Sprinkle sea salt.
Roll dough into a log, starting at the longer side. Slice the log into 12 equal parts. Place rolls in a greased 9 x 12-inch baking pan. Cover with plastic wrap and let rolls rest for 30-45 minutes at room temperature to allow rolls to rise.
Preheat oven to 350°F. Remove plastic wrap and bake rolls for 30-35 minutes until golden brown on top and the internal temperature of the rolls hit 185°F. Allow rolls to rest for 5 minutes to slightly cool.
Cream Cheese Frosting: Beat together cream and butter until smooth. Add sifted powdered sugar and beat until smooth and thickened. Spread over warm cinnamon rolls. Top rolls with additional confetti sprinkles, if desired.