Move rack to upper third in oven and preheat oven to 425°. Line muffin tin with cupcake liners. In a large mixing bowl, whisk together flour, sugar, baking powder, baking soda, and kosher salt. In a smaller bowl, whisk together egg, buttermilk, butter, and almond extract. Add wet ingredients to dry and mix just until combined. Fold in sprinkles.
Transfer batter to lined muffin tins and bake for 15-18 minutes. Let cool in pan for 5 minutes, then transfer muffins to a wire rack to cool completely.
Glaze
Once muffins have cooled completely, prepare glaze. Whisk together powdered sugar, buttermilk, and corn syrup. Adjust buttermilk as needed to get a thick pourable consistency. Spoon over bread and top with nonpareils.