Make the pancake batter up to a day ahead, or just before cooking. Tip the flour, baking powder, cinnamon and 2 tsp sugar into a bowl, add a good pinch of salt and combine with a whisk. Add the eggs, buttermilk or yogurt and milk to the bowl and whisk into a smooth batter. If making ahead, cover and chill until ready to cook.
Tip the blueberries, cherries, cornflour, 2 tbsp sugar and the vanilla into a pan, and stir until the berries are coated in cornflour. Add 1 tbsp water, then place over a high heat and bubble for a minute or 2 until syrupy but the berries are still holding their shape. Set aside to cool, then remove the vanilla pod, if using. This is best served warm.
Heat the grill to medium-high and arrange the bacon on a baking tray lined with foil. Set aside. If you have a separate oven, heat this to a low setting (50C/30C fan/gas ½) with a baking tray in it (this is to keep the pancakes warm as you cook them). If not, they can sit under the bacon, just keep a close eye on them.
Heat a glug of oil in a large, heavy frying pan, wipe the oil around the pan with a piece of kitchen paper, leaving a fine coating of oil on the surface. Transfer the pancake batter to a jug. When the pan is hot but not smoking (keep it over a moderate heat) pour the batter into the pan, making 7-8cm pancakes, with plenty of space between them (you should fit three pancakes in at a time). The batter should sizzle a little as it hits the pan, but not aggressively – adjust the heat if you need to. Cook each pancake until the underside is golden; by this time bubbles should be appearing on the surface and the edges beginning to set, indicating that the pancake is ready to flip over. Use a fish slice to do this. They should take roughly 2 mins on each side. Transfer the pancakes to the warm baking tray. Wipe a little more oil around the pan and continue cooking the rest of the batter in this way. You should make 12 pancakes.
When you’re halfway through the batter, grill the bacon for 4-5 mins on each side until crispy.
To serve, stack the pancakes with a dollop of mascarpone, bacon, and fruits between each layer, and serve with a jug of maple syrup.