Lynette Sallee has practiced making her cinnamon rolls more times than she can count: She bakes about 100 of her signature frosted twists around the holidays alone. The treats took first place in 2013 at the Montana Winter Fair in part because of the topping, she says. "The sprinkles are kind of a must."
Make the dough: Warm the milk in a small saucepan until steaming. Dissolve the yeast in 1/2 cup warm water in a large bowl. Add the milk, shortening, eggs, 1/2 cup granulated sugar, the salt and 7 cups flour; mix with a wooden spoon until combined. Transfer the dough to a lightly floured surface and knead until smooth and elastic, adding up to 1/2 cup more flour if the dough is too sticky. Transfer to a lightly oiled bowl and cover with plastic wrap; let rise in a warm place until doubled in size, about 1 1/2 hours.
Lightly oil 2 baking sheets. Combine the cinnamon and the remaining 2 tablespoons granulated sugar in a small bowl. Roll out the dough on a lightly floured surface into a 12-by-24-inch rectangle, with a long side facing you. Spread the butter over the right half of the rectangle, leaving a 1-inch border around the edges; sprinkle with the cinnamon sugar.
Fold the left half of the dough over the cinnamon sugar, like closing a book. Cut the folded dough crosswise into twelve 1-inch-wide strips. Take one strip and twist several times, stretching the dough a little; hold one end of the strip against a baking sheet and wind the strip around to form a coil, tucking the other end underneath. Repeat with the remaining strips, spacing the rolls about 2 inches apart on the baking sheets. Lightly cover the baking sheets with plastic wrap and let the rolls rise until doubled in size, about 1 hour.
Preheat the oven to 375 degrees F. Uncover the rolls and bake until lightly browned, 25 to 30 minutes. Make the glaze: Beat the confectioners' sugar, butter and salt in a bowl with a mixer on medium-high speed until combined, about 3 minutes. Slowly beat in up to 1/4 cup boiling water until pourable. Drizzle over the warm rolls and top with sprinkles.