In the bowl of a mixer fitted with a paddle attachment, cream the butter, sugar and powdered sugar. Add the vanilla and salt. Add the flour and mix until dough begins to from. Don't over mix it. Dough should be a little crumbly.
Press 2/3 of the dough into the bottom of the pan. Reserve the other 1/3 for the crumble topping.
Bake the crust at 350° for 18-20 minutes until lightly browned. Allow crust to cool slightly.
Spread the crust with strawberry jam. You can make your own or use a store bought jam for convience.
Crumble the reserved topping over the strawberry jam.
Return the bars to the oven and bake for an additional 25 minutes until the jam is bubbly and the streusel is browned.
Allow bars to cool completely before cutting into 9 squares. Dust with powdered sugar before serving.