Place a rack in the upper third of the oven and preheat oven to 425 degrees F.
Line a rimmed baking sheet with parchment paper and set aside.
In a medium bowl, whisk together flour, baking powder, salt, and sugar. Use a grater to shave in the butter (this will make your biscuits extra fluffy!), and add to the bowl with the flour. Work the dough with very clean fingers or a pastry cutter until it looks a bit crumbly.
Make a well in the center and add your strawberries. Use a spatula to fold them in to the flour mixture.
Mix the vanilla and cream together in a measuring cup.
Add the cream mixture to the flour mixture and use your hands to gently mix it all together. The dough should be a bit shaggy, but hold together well.
If it's not quite holding together, add 1 - 2 more tablespoons of cream at a time.
The dough should be moist and cohesive, but not sticky.
Turn the dough out onto a lightly floured work surface. Gently gather and knead the dough, then, using a pastry cutter, cut into 2 disks.
Roll each disk out until they're about 1 1/2" thick.
Use the pastry cutter (or a sharp knife) to cut each disk into 6 even triangles.
Place them 1-inch apart on the prepared baking sheet and use a silicon brush to brush the tops lightly with cream.
Sprinkle tops with a little demerara sugar, then bake for 18-20 minutes or until golden brown and cooked through.
Remove from the oven and transfer to cooling rack.