For the biscuits: Preheat oven to 400F/200C. Line a large baking sheet with parchment paper or a silicone baking mat. Set aside.
In a large bowl, mix together flour, baking powder, salt, and sugar until combined. Cut in butter using a pastry blender until mixture resembles coarse meal. Alternately, you can pulse the ingredients in a food processor. Having uneven pieces of butter throughout is ok.
In a small bowl, whisk together egg, 1/2 cup heavy cream, and vanilla extract, then add it to the flour mixture. Gently toss with a rubber spatula until dough begins to form. Avoid over mixing. Transfer dough to a floured surface and knead gently, about 5-6 times, until a ball forms (if dough is too sticky, add a bit more flour). Pat dough into a 9x6-inch rectangle, about 3/4-inch thick. Using a 2.5-inch (6.5cm) biscuit cutter, cut out 6 rounds. Press the leftover dough into another ¾-inch thick piece and repeat the process to get 2-3 more biscuits.
Place biscuits on prepared baking sheet. Brush tops with heavy cream and sprinkle with coarse sugar. Bake for 15-18 minutes, or until golden brown and a toothpick inserted into the center comes out clean. Transfer baking sheet to a wire rack and allow to cool for 10 minutes. While biscuits are still hot, sprinkle again with coarse sugar for extra crunchiness.
Biscuits are delicious either warm or at room temperature. They are best eaten the same day they’re made, but can be frozen for up to 1 month. Reheat in the oven before serving if you want to serve them warm.
For the strawberries: Place 1/3 of the strawberries in a bowl and crush them using a potato masher or fork. Slice the remaining strawberries into quarters or smaller cubes and add them, along with the sugar, to the crushed strawberries. Let sit for at least 30 minutes (or several hours) at room temperature to let the strawberries macerate and release their juices.
For the whipped cream: In a mixer bowl fitted with the whisk attachment, whisk heavy cream, sugar, and vanilla on high speed until stiff peaks form. Avoid overbeating.
Assembling the shortcakes: Cut each biscuit in half, and place the bottom of each half on a serving dish. Spoon on strawberries and whipped cream, then top with the other half of the biscuit. Serve immediately.