01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - In a large bowl, whisk together the flour, sugar, baking powder, and salt. Add the cubed cold butter and cut it in using your fingers or a pastry blender until the mixture resembles coarse crumbs with pea-sized pieces of butter remaining.
03 - In a small bowl, whisk together the heavy cream and egg until combined. Pour the wet mixture into the dry ingredients and stir gently with a fork just until the dough comes together. Do not overmix.
04 - Turn the dough out onto a lightly floured surface and gently pat it into a round about ¾ inch thick. Using a knife or small cutter, cut the dough into 1-inch squares or rounds suitable for individual trifle layers.
05 - Arrange the shortcake pieces on the prepared baking sheet. Bake for 12 to 15 minutes until the tops are golden brown. Transfer to a wire rack and let cool completely.
06 - Place the sliced strawberries in a bowl and toss with the granulated sugar and lemon juice. Let stand at room temperature for at least 15 minutes until the berries release their natural juices and form a light syrup.
07 - In a chilled mixing bowl, combine the heavy cream, powdered sugar, and vanilla extract. Beat on high speed with an electric mixer until stiff peaks form, being careful not to over-whip.
08 - In each serving glass, place a layer of shortcake pieces, followed by a spoonful of macerated strawberries and their juices, then a generous dollop of whipped cream. Repeat the layers once more, finishing with a final swirl of whipped cream topped with a few fresh strawberry slices.
09 - Serve the trifles immediately, or cover and refrigerate for up to 2 hours before serving to allow the flavors to meld.