Transfer the mixture to the prepared pan, and par-bake for 20 minutes. Spread a thin layer of jam over the partially baked shortbread (it's ok if it's still hot from the oven).
Bake until just barely beginning to turn golden on top (approximately 30 to 40 minutes). Cool completely, then cut into squares and garnish with powdered sugar.
When I find myself with a few free moments, I head straight for my kitchen! I'm a former pastry chef who still loves to bake, & to share how easy and fun baking from scratch can be!