Preheat your oven to 350°F (175°C). Line an 8x8 inch baking pan with parchment paper, leaving an overhang on two sides for easy removal.

In a large bowl, cream together the softened butter and granulated sugar using an electric mixer until light and fluffy (about 3 minutes).

Beat in the vanilla extract. Gradually add the flour and salt, mixing on low speed until just combined and a soft dough forms. Do not overmix.

Press about two-thirds (2/3) of the dough evenly into the bottom of the prepared baking pan. Sprinkle evenly with the apricot jam, spreading it gently to the edges.

Crumble the remaining one-third (1/3) of the dough evenly over the top of the jam layer. This will create the streusel topping.

Bake for 30 to 35 minutes, or until the edges are golden brown and the topping is lightly set. Let cool completely in the pan on a wire rack (this is crucial for clean cutting).

Once fully cooled, use the parchment paper overhang to lift the bars out of the pan and slice into 16 even squares.