Preheat the oven to 180°C, 160°C fan, gas 4. Line a 12-hole muffin tin with squares of baking paper (measuring about 14cm). Don't worry if the paper sticks out the tops.
Beat the eggs together with the milk and crème fraîche. Stir through the ham, Cheddar and spring onions; set aside.
Divide the baguette pieces between the muffin-tin holes, then spoon over the egg mixture. Let sit for about 30 minutes to allow the egg mixture to soak into the bread.
Bake the stratas for 30-35 minutes until set (when a skewer comes out clean) and golden.
Cook's tip: sprinkle over some sesame or poppy seeds before baking for an extra burst of flavour.