01 - Preheat oven to 350°F. Line a 9x13-inch baking pan with parchment paper, leaving overhang for easy removal.
02 - In a large bowl, beat softened butter and granulated sugar together until light and fluffy, about 2-3 minutes.
03 - Beat in eggs one at a time, mixing well after each addition. Stir in vanilla extract.
04 - In a separate bowl, whisk together flour, baking powder, and salt until evenly combined.
05 - Gradually add dry ingredients to wet ingredients, mixing until just combined. Do not overmix.
06 - Press two-thirds of the dough evenly into the bottom of the prepared pan, creating a smooth layer.
07 - Spread strawberry jam evenly over the dough base, leaving a small border around the edges.
08 - Crumble remaining dough over the jam layer. Press gently to adhere without creating a solid layer.
09 - Bake for 23-27 minutes until edges are golden brown and center is set. Cool completely in pan on wire rack.
10 - Whisk powdered sugar, milk, and vanilla extract until smooth and pourable. Adjust consistency with more milk if needed.
11 - Drizzle glaze evenly over cooled bars. Immediately sprinkle with colorful sprinkles before glaze sets. Let stand 15 minutes before cutting.