01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - In a mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, and salt until evenly combined.
03 - Add the cubed cold butter to the flour mixture. Using your fingers or a pastry blender, cut the butter in until the mixture resembles coarse crumbs with pea-sized pieces remaining.
04 - In a separate small bowl, whisk together the heavy cream and egg. Pour the wet mixture into the dry ingredients and stir gently just until the dough comes together. Do not overmix.
05 - Turn the dough out onto a lightly floured surface and gently pat it into a ¾-inch thick round. Use a 1-inch biscuit cutter or knife to cut small rounds or squares suitable for layering in trifle glasses. Re scraps and repeat.
06 - 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.
07 - Place the sliced strawberries in a bowl and toss with granulated sugar and lemon juice. Let stand at room temperature for 15 minutes until the berries release their natural juices.
08 - 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. Be careful not to overwhip.
09 - In individual serving glasses, layer shortcake pieces, macerated strawberries with their juices, and whipped cream. Repeat the layers once more. Finish with a generous dollop of whipped cream and garnish with a few fresh strawberry slices. Serve immediately or refrigerate for up to 2 hours before serving.