1. Make sure the butter cubes, cream, and milk are as cold as possible. I like to put them in the freezer for 10 minutes before starting.
2. Have ready a baking sheet lined with parchment paper. 

By hand: 

1. Stir together flour, baking powder, salt, and sugar in a large bowl. 
2. Add butter and integrate with your hands or a pastry cutter until it’s the size of peas. Don’t overwork it. The butter should remain cold. If it’s starting to become extremely soft put the bowl in the refrigerator or freezer until the butter becomes cold again. 

Food processor:

1. Put the flour, baking powder, salt, sugar, and cinnamon in the bowl of the food processor. Pulse a few times to integrate.  
2. Add cold butter pieces and pulse on/off until the butter is the size of peas. The only thing to watch out for is not getting carried away and processing the butter too much. 
3. Transfer the mixture to a large bowl. 

For both methods:

1. Beat the egg slightly and add to the butter mixture with milk, cream, and vanilla. 
2. Mix lightly with a fork or spoon. It will be floury but, if you take some of the dough in your hand and squeeze, it will come together. 
3. Add blueberries and mix lightly, trying not to crush them. 
4. Transfer this whole shaggy mass to a clean surface.
5. With your hands (I use a cornet to aid me) start bringing the dough together, folding it onto itself as best as you can. Don’t knead it as you would a pie dough. It only needs to be patted into a rough circle. (I recommend you watch the video in the blog post for guidance). There will be floury patches. 
6. Transfer the dough circle to the prepared baking sheet. Cut in half and each half in 3 wedges with a kitchen knife or the dough scraper. 
7. Pop into the freezer for 10 minutes or the refrigerator for 20 minutes while preheating the oven. 
8. Preheat oven to 375°F/190°C. 
9. Bake for 10 minutes, turn the oven down to 350°F/180°C, and continue baking for about 20 minutes until the top is golden and dry. 
10. After 30 minutes, take out the sheet and check that the scones are done by carefully lifting the top of one and checking that the inside is done and not still raw. Bake for 5-10 more minutes if needed. 
11. Let cool on a wire rack.
12. Store at room temperature for 1-2 days and warm slightly in the oven before eating.