Slice the cold butter into small cubes and place in the fridge or freezer (make sure the butter is very well chilled at the time of using).
Preheat oven to 400 degrees. Line a baking sheet with parchment paper.
In a medium size bowl, combine the shortcake dry ingredients (flour, baking powder, sugar and salt).
Add the cold butter and blend with the dry ingredients using your fingertips or a pastry cutter. After mixing, the butter should still be visible as small, pea-sized shapes.
To prepare the homemade buttermilk, stir one tablespoon of lemon juice (or vinegar) with 3/4 cup milk and let it sit at room temperature for 30 minutes.
Pour the buttermilk into the butter and flour mixture and stir with a wooden spoon just until combined. At this stage, the dough should be sticky and crumbly (be sure to not overwork the dough).
Place the dough onto a floured surface and fold it over itself 2 to 3 times until it holds together.
Roll out the dough into a rectangle with around 1 inch thickness. To create a round shortcake slice, cut straight down using a biscuit cutter or round cutter.
Arrange the biscuits on the prepared baking sheet. Brush the top with heavy cream and bake in the preheated oven for 10 to 15 minutes until golden brown.
At the time of serving, slice the shortcake horizontally in half. Spread 1 tablespoon of strawberry coulis on the bottom half, then layer the macerated strawberry and whipped cream, place the other half of the shortcake on top and add more strawberry coulis. Decorate with fresh strawberries, a spoonful of whipped cream, and fresh mint or basil leaves.