In a bowl, pour the rum over the strawberries and let them stand for an hour, then drain them well. Mix 3 1/3 tbsp (50 g) of soft butter with 4 tablespoons of sugar, ground oatmeal and 1 tsp vanilla. Soak the drained strawberries with this mixture and mix carefully.
For the dough, mix 1/5 cup (60 g) soft butter with 1 cup of sugar, eggs and cream with a fork or whisk. Mix the flour with the baking powder and vanilla and combine the dry mixture with the liquid one. Pour the mixture in a form with removable walls, covered with baking paper and lightly greased.
Top with the flavored strawberries. Put the cake to bake in a low oven at about 338°F (170 °C) for about an hour or until risen. Leave the finished cake for 15 minutes in the form, remove the walls and sprinkle it with powdered sugar.