Preheat the oven to 325°F. Line a 9×13 baking dish or a quarter sheet pan with parchment paper.

In a large bowl, or stand mixer fitted with the paddle attachment, combine butter and sugar. Mix on medium speed until light and fluffy.

Add the egg yolk and vanilla and beat until combined.

Add the flour and salt to the butter mixture and mix on low speed until a soft dough forms. Do not overmix.

Press approximately ½ of the dough into the prepared baking pan and bake in a preheated oven for 10 minutes or until a very light golden brown.

Refrigerate the remaining dough.

Let the bottom crust cool. Spread the raspberry jam over the crust.

Crumble the reserved dough over the top. Bake at 325°F until golden brown, about 20-30 minutes.

Let the bars cool for at least 4 hours before cutting into squares.