Preheat oven to 350°F (180°C, or gas mark 4). Line an 8-inch (20-cm) square baking pan with parchment paper.
Using an electric mixer, combine the butter, sugar, peanut butter, vanilla and faux egg.
Add flour, baking powder and salt, and stir until just combined.
Using your hands or an offset spatula, press down or spread 2/3 of the dough into the prepared pan.
Spread the jam evenly on top, leaving 1/2 an inch around the edges.
Crumble remaining dough evenly on top of the jam.
Bake for 30 minutes, until the top is golden brown. Place the pan on a wire rack to cool 15 minutes. Carefully transfer the parchment paper and bars onto the wire rack and let cool completely before placing in the fridge to chill, as these are tastiest served cold. Slice away and enjoy.