Heat oven to 375. Line an 8x8 cake pan with parchment paper.
In a stand mixer with paddle, cream the butter, sugar and vanilla on medium until light and fluffy, scraping down the bowl a few times, about 5 minutes.
Add the eggs one at a time, mixing well after each.
Press half the dough into the bottom of the pan. It is sticky so using clean wet hands helps spread it around without it sticking to your fingers.
Spread the jam over the bottom layer of dough.
Using wet hands again, pick up 2 tbsp size amounts of dough and stretch them a bit thin so you can place them on the top. Once you place them all, gently smooth the dough. You don't want to disturb the jam. Alternatively, you can place each 1/2 of the dough spread out in 2 8x8 pans and freeze them for about 15 minutes then stack in one of the pans with the jam in between.
Bake for 20-23 minutes until set and browned on top. When the top looks nicely browned, cover with foil loosely and bake 5-8 more minutes to be sure the bottom crust is also fully cooked.
Cool for 10 minutes remove from the pan by lifting the parchment. Cool fully on a wire rack and then top with glaze and sprinkles.