Preheat oven to 400°. Line a rimmed baking sheet with parchment paper.
Referring to step-by-step how-tos on page 126, on a lightly floured surface, unroll puff pastry. Brush a thin layer of water onto 1 pastry sheet. Place remaining pastry sheet on top, and gently press to adhere. Using a 2-inch square cutter, cut 16 squares from pastry stack. Place squares on prepared baking sheet. Using a 1½-inch square cutter, cut halfway through centers of pastry squares, just enough to leave an imprint. Using a fork, poke several holes in center square imprint.
Bake until edges of pastry squares are golden brown, 15 to 18 minutes. Let cool on a wire rack. Store in an airtight container at room temperature until needed, up to 1 day.
Line another rimmed baking sheet with foil.
In a medium bowl, stir together Brussels sprouts, bacon drippings, salt, and pepper. Transfer Brussels sprouts to prepared baking sheet, and spread in an even layer.
Bake until crisp, 18 to 20 minutes. Transfer to a large heatproof bowl. Add Bacon Jam, stirring until combined.
Using a paring knife, gently cut along center imprints, being careful not to cut through bottoms. Using a finger, gently press down center of each square. Divide Brussels sprouts mixture among wells of pastry squares. Serve immediately.
Recipe by TeaTime Magazine at https://teatimemagazine.com/bacon-jam-brussels-sprouts-squares/