Pre-heat your oven to 400°F, and line a baking sheet with parchment paper.
In a large bowl, whisk together flour, sugar, baking powder and lemon zest.
Use a pastry blender to cut the butter into the flour until the mixture resembles course crumbs.
Stir in the blueberries.
Pour in the cream and vanilla. Use a fork to stir the mixture, taking care not to crush the blueberries. It should start to form a dough. Keep stirring until you've incorporated as much of the flour as you can (you'll still have some crumbly flour bits).
Turn the mixture out onto a clean, flat surface. It will be quite crumbly to start. Gather all the crumbs and dough together and gentle press it into a rough disc shape, about an inch thick.
Slide a pastry scraper under the dough and use it to fold the dough in half. Press the mixture down into a disc shape again. Repeat the folding process a few times until the crumbs have been incorporated and the dough holds together. Try not to overwork the dough too much.
Once your dough is holding together in a nice disc shape, cut it into 8 triangles and place on your parchment lined baking sheet 2-3 inches apart. Bake for 20-25 minutes until the tops are golden brown.