Chocolate Cinnamon Rolls

Dissolve yeast in warm water in a mixing bowl. Stir in 2 1/2 cups flour, cocoa, shortening, milk, 1/2 cup sugar, eggs, 1 tablespoon cinnamon, and salt. Beat with an electric mixer until smooth. Mix in enough remaining flour to make dough easy to handle.

Turn dough onto a lightly floured board; knead until smooth and elastic, about 5 minutes. Place in a greased bowl, turn greased side-up, and cover. Let rise in a warm place until doubled in size, about 1 1/2 hours.

Preheat the oven to 375 degrees F (190 degrees C). Grease two 9x13-inch baking pans.

Punch down dough and divide in half. Roll each half into a 15x9-inch rectangle. Spread each rectangle with 2 tablespoons butter. Mix remaining 1/2 cup sugar and 1 tablespoon cinnamon together in a bowl. Sprinkle half of the mix over each rectangle. Roll up, beginning at the wide side; pinch edges of dough into the roll to seal well. Stretch the roll to make even.

Cut each roll into 15 slices. Place slightly apart in the prepared pans. Let rise until doubled in size, about 30 minutes.

Bake in the preheated oven until golden, 25 to 30 minutes.

While rolls bake, mix confectioners' sugar, milk, and vanilla extract in a bowl until smooth. Frost rolls while still warm.