Preheat oven to 350 degrees.
Butter a 9-inch tube pan with a removable bottom or a bundt pan.
In a medium-sized bowl whisk together flour, baking powder, and salt.
In the bowl of a stand mixer or in a large bowl with a hand mixer, beat butter and granulated sugar on medium speed until pale and fluffy, about 2 minutes.
Beat in eggs, 1 at a time, until well blended. Mix in vanilla.
Mix in flour mixture in 3 additions, alternating with milk.
Stir in ½ cup sprinkles.
Spoon half of the batter into the prepared pan. Sprinkle the streusel middle mixture over the batter. Top with remaining cake batter, making sure to spread evenly.
Sprinkle streusel topping mixture evenly over batter.
Bake until cake is golden brown, about 50-55 minutes, until a toothpick inserted into the center comes out clean.
Move pan to a wire rack to let cool completely before removing from pan.
If using a bundt pan, carefully place sheet pan or cutting board on top of cake and flip until cake comes lose from pan. Now flip cake back onto cake server.
Drizzle glaze evenly over the top of the cake and top with remaining ¼ cup sprinkles.