Hull strawberries and cut in half or quarters, depending on size. Mix with sugar and place in refrigerator while you make the shortbread. This will allow juices to develop.
Using a whisk attachment for your hand or stand mixer, beat 1 ½ cups heavy cream on medium-high speed until it thickens. Add in sugar and vanilla, and continue beating until soft peaks form. Store in refrigerator until ready to use.
Preheat oven to 425 degrees.
In a large bowl, sift together flour, 3 tablespoons sugar, salt, and baking powder. Cut butter into the flour mixture with a pastry cutter, or using the pulse-feature of a food processor, until coarse crumbs form.
Add heavy cream and mix until combined. The dough will still be very crumbly. Turn onto a floured surface and pull all dough together to form a ball. Knead for one minute. Roll dough ½-inch thick and cut into 3-inch circles using a biscuit cutter or a dinner glass.
Place onto a lined or greased baking sheet, close together where they are touching. Brush each shortcake with remaining heavy cream and sprinkle with coarse sugar. Bake 10-15 minutes, until golden brown. Cool for 10 minutes before assembling.
Slice each shortcake horizontally and layer with strawberries and whipped cream. Serve immediately.