Adapted from Fine Cooking
4 cups flour
1 package Rapid Rise yeast (2 1/4 teaspoons)
1/2 cup sugar
1 teaspoon salt
1 cup whole milk
1 stick (4 ounces) butter
3 egg yolks
3/4 cup brown sugar
1 1/2 tablespoons cinnamon
Pinch of salt
4 tablespoons butter, at room temperature
1/2 stick (2 ounces) butter, melted
2 cups powdered sugar
1/2 teaspoon vanilla
Milk or cream to thin
In a large bowl of an electric mixer, whisk together flour, yeast, sugar and salt. Attach bowl to mixer with a dough hook attached. Microwave butter and milk till butter is melted. Allow to cool to between 115-125º.
Add the butter mixture and the egg yolks to the mixer. Mix on low speed till combined, then increase speed to medium high and beat for about 8 minutes, till dough pulls away from the bowl. Adding a little extra flour may be necessary. Cover with plastic wrap and let rise in a warm place till doubled in size...from 45-90 minutes depending on the temperature of your kitchen.
Grease a 9 x 13 inch baking pan. Roll dough out on a lightly floured surface to about a 12 x 20 inch rectangle. Spread with softened butter. Mix together brown sugar, cinnamon and salt. Sprinkle evenly over dough. Roll dough from the long side nearest you to the long side away from you. Using dental floss, a knife or a bench scraper, cut the log into 12 equal pieces. Trim a small amount from each end first, if uneven.
Lay the rolls flat side down into the prepared baking pan. Cover with greased plastic wrap and allow to rise in a warm spot till rolls are almost doubled, puffy and nearly touching, 30-45 minutes. Preheat oven to 350º and bake about 20 minutes. Cool slightly before icing.
To make icing, combine melted butter and powdered sugar. Add milk or cream to thin to desired consistency. Add vanilla.