1: In a small saucepan over low heat, melt 100 g butter, then remove from heat and add 50 g cream and 2 tablespoons Calvados (apple liqueur), stir and set aside.
4: Drizzle in the butter, cream and calvados mixture without stopping the mixer.
5: Mix well.
6: Increase the mixer speed, and let the dough beat for 10 minutes. Note: This is an essential step if you then want a light, airy cake.
7: Pour the dough into a buttered high-sided tin, cover with cling film or plastic sheeting, and leave to stand in a warm place for around 2 hours.
8: At the end of this time, you'll see that the dough has pushed through.
9: Preheat your oven to 180°C (360°F) and bake for 25-30 minutes.
10: Unmould as soon as you remove from the oven, otherwise the cake will stick to the tin, and leave to cool on a wire rack.
Remarks
If using semi-salted butter, do not add salt at rstp=2. The Saint-Lô cake recipe is said to have been invented by a local restaurateur called "Le père Féret", chef of the Marignan restaurant. The 10 minutes when the dough is beaten in step 6 are very important. If you don't do this (as in many recipes on the web), you'll end up with a dense cake that won't taste as good.