Mini King Cupcakes

INGREDIENTS

• 1/2 cup warm whole milk (110°)
• 2 (1/4-ounce) packages dry yeast
• 1/3 cup sugar, divided
• 1/2 cup unsalted butter, melted
• 3 egg yolks
• 1/2 teaspoon vanilla extract
• 1/2 teaspoon lemon zest
• 3 teaspoons fresh lemon juice, divided
• 1 1/2 cups all-purpose flour
• 1/2 cup cake flour
• 1 tablespoon ground cinnamon, divided
• 1/4 teaspoon kosher salt
• 1 large egg, lightly beaten
• 1 cup powdered sugar
• 1 1/2 tablespoons hot water
• Purple, green, and yellow sugar sprinkles