Preheat oven to 180°C/200°C/400°F. Line a large baking pan with parchment paper or baking paper.
Remove the dough from the fridge and let it sit at room temperature for 10 minutes to soften.
Lightly flour a work surface. Roll out the dough into a 12-inch (30cm) circle, dusting with more flour as needed. The circle doesn't have to be perfect. You can trim off any ragged edges to make a clean, even circle, if you like. Carefully use the rolling pin to transfer the dough onto the prepared baking sheet.
Spoon the strawberry filling into the centre, leaving a 2-inch (5cm) border. Gently fold the pastry over the filling, creating soft pleats around the edges.
Crack the egg into a small bowl and whisk until well combined. Brush the egg wash gently over the pleated edges and sprinkle flaked almonds.
Bake in the oven for 30-35 minutes, rotating halfway to ensure the galette bakes evenly.
Transfer to a wire rack and leave to cool for 10 minutes before slicing and serving. Serve warm or at room temperature