Beat the eggs in a bowl with the sugar, cinnamon and milk. Heat the butter in a large, heavy-based frying pan. Dip the brioche slices, 2 at a time, into the egg mixture on both sides, then lift into the hot pan and fry for 1–2 minutes on each side until golden.
Repeat with the remaining brioche slices. Mix half the blueberries into the yogurt.
Serve the warm French toasts with spoonfuls of the yogurt on top, the remaining blueberries scattered over and a thin drizzle of honey on top.