Make sure you have all the ingredients at hand. Preheat the oven to 200°C.
Wrap the sweet potatoes (in their skin) in aluminium foil and bake them in the oven for at least 30 minutes, until they soften up but are still slightly undercooked in the centre (check using a wooden stick).
Take the sweet potatoes out of the oven, take of the aluminium foil and leave them to cool. When they have cooled down, peel them and cut them into slices.
Roll out the puff pastry to about 2mm thick on a lightly floured work surface. Cut out rectangles in any size you wish and place them on a sheet with baking parchment, spaced apart. Prick them all over with a fork and chill in the fridge for at least 30 minutes.
Meanwhile, finely chop the garlic and parsley. Put in a small bowl and add the olive oil and a pinch of salt. Stir around.
Remove the pastry from the fridge. Beat the egg and brush the pastry lightly with it. Then spread a layer of soured cream on top, leaving a small border all round.
Arrange the sweet potato slices on the pastry, slightly overlapping, and keeping the border clear. Season with freshly ground black pepper if desired.
Add the grated goats' cheese and the pumpkin seeds on top of the pastry. De-seed and finely chop the red chili pepper and sprinkle the pastries with it.
Bake the galettes at the top of the over for about 20 minutes, or until the pastry is cooked through; it should be golden brown. Drizzle some of the parsley mixture on top before serving.