01 - Preheat oven to 400°F. Line a baking sheet with parchment paper and set aside.
02 - In a large mixing 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 throughout.
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 just until a soft dough comes together. Avoid overmixing.
04 - Turn the dough out onto a lightly floured surface and gently pat it into a ¾-inch thick round. Using a knife or biscuit cutter, cut the dough into small squares or rounds about 1 inch in size, suitable for layering in individual trifle glasses.
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 allow to 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 15 minutes until the berries soften and release their natural juices.
07 - In a chilled mixing bowl, combine the cold heavy cream, powdered sugar, and vanilla extract. Beat on high speed using an electric mixer until stiff peaks form. Be careful not to overwhip.
08 - In individual serving glasses, create layers starting with shortcake pieces at the bottom, followed by a generous spoonful of macerated strawberries and their juices, then a dollop of whipped cream. Repeat the layers once more, finishing with a final swirl of whipped cream and a few fresh strawberry slices on top.
09 - Serve the trifles immediately, or cover and refrigerate for up to 2 hours before serving to allow the flavors to meld.