Preheat oven to 325℉. Grease and flour a 9 x 5" loaf pan. Line two 9 x 12" rimmed baking sheets with parchment paper. This will be for the petit fours.
Sift flour and baking powder in a medium bowl and set aside.
3 ½ cups flour, 1 teaspoon baking powder
In the work bowl of a stand mixer, cream butter, cream cheese and sugar for 6 minutes, until mixture is light in color and airy. Add eggs one at a time, mixing well after each addition. Add vanilla and milk until combined.
1 cup butter, 8 ounces cream cheese, 3 cups sugar, 1 teaspoon vanilla, 6 eggs, 1 cup milk
With mixture on low, add flour mixture until completely combined, without over mixing.
Pour batter ¾ way into loaf pan and divide remaining batter between prepared baking sheets.
Bake loaf for 60 to 65 minutes until a toothpick inserted in the center comes out clean. Bake sheet pans 30 to 40 minutes until edges are browning and each pan tests done with the toothpick method.
Remove from oven and cool 10 minutes on wire racks, then remove from pan to cool completely. Remove parchment when you remove from the pans.
In a small bowl, whisk strawberry jam (with a small whisk) until it is spreadable. Spread in a thin, even layer over one cake from the sheet pan. If you feel you want more of a filling, use more jam and repeat. Top with second cake, so you have two layers.
½ cup seedless strawberry jam or preserves
Using a sharp knife, cut one in squares. Line a baking sheet with foil and put a cooling rack on top. Place squares about 1" apart.
Make poured glaze: In a large sauce pan, over low heat, combine all glaze ingredients except sprinkles. Stir until smooth, remove from heat.
7 ½ cups powdered sugar, sifted, ¼ cup light corn syrup, ½ teaspoon vanilla, 1 teaspoon lemon zest, ⅓ cup water, Sprinkles
Spoon glaze over squares. Let set. Spoon a second coating, a few at at a time, and decorate with sprinkles. If glaze begins to thicken, warm in for a minute or so. Let glaze set before serving.
Can be stored, covered for up to 2 days.