Dough: In the bowl of stand mixer, sprinkle yeast over warm water. Add 1 teaspoon sugar and stir to combine. Let sit for 5-7 minutes to allow mixture to bubble and activate.
Add remaining ¼ cup sugar, milk, egg, egg yolk, and salt. Whisk until eggs are thoroughly combined. Add 2 cups of flour to mixing bowl. Use the hook attachment to mix dough together. Mix on low speed until flour is incorporated. Add another cup of flour.
Continue to knead on low speed, adding softened butter one tablespoon at a time. Add remaining cup of flour and knead until dough is smooth and no longer sticks to the sides of the bowl. If dough is too sticky, add additional one tablespoon of flour.
Transfer dough to a large greased bowl. Cover with kitchen towel or plastic wrap and let dough rest at room temperature for about an hour until dough has doubled in volume.
Punch down risen dough. Transfer to a lightly floured working surface. Roll dough into a 20x14-inch rectangle.
Cinnamon Sugar Filling: Spread ⅓ cup softened butter over dough. In a small bowl, mix together sugar, brown sugar, cinnamon and pinch of salt. Sprinkle cinnamon sugar filling over dough.
Using a ruler and sharp knife (or pizza wheel cuter) divide the dough into 2 ¼-inches x 20 inches horizontal strips. Working from right to left, roll one strip into a snail like form. Align the tail of the snail roll with the the beginning of the next horizontal strip. Continue to roll into a larger snail. Repeat this with the remaining dough strips until you have one giant cinnamon roll.
Place giant cinnamon roll into a 9-inch springform pan. Cover with plastic wrap or kitchen towel and let dough rest for 45 minutes at room temperature, until dough has expanded and risen.
Preheat oven to 350°F. Remove plastic wrap or kitchen towel. Bake cinnamon roll for 20 minutes, rotate pan, and bake for another 20 minutes. At this point the top of the cinnamon roll should be golden brown. Place foil on top fo the cinnamon roll to prevent it from burning. Bake for another 15-20 minutes until the internal temperature of the cinnamon roll registers at 185 degrees F. Allow cinnamon roll to rest in pan for 10 minutes before unmolding from springform pan.
Cream Cheese Frosting: Beat together cream cheese and butter until smooth. Add powdered sugar, salt, and vanilla. Continue to beat until smooth and thickened. Scrape down bowl as needed to ensure thorough mixing. Spread over warm or room temperature cinnamon roll. Top with confetti sprinkles. All images and text ©The Little Epicurean.