Preheat the oven to 350°F/180°C. Line the bottom of a 25cm cake tin with baking parchment and grease the sides.
In a large bowl, combine the flour, sugar, baking powder and salt. In a another bowl, whisk the eggs, ricotta and vanilla until smooth. Fold the wet ingredients into the dry ingredients until just blended.
Fold in the butter followed by 1 cup blackberries, taking care not to crush the berries. Scrape the batter into the prepared tin and scatter the remaining blackberries over the top.
Bake the cake until golden brown, about 50-60 minutes or until a skewer comes out clean. Let it cool at least 20 minutes before unmolding. Serve at any time of day.
Notes
Adapted from Alison Roman's Raspberry-Ricotta Cake
You can use fresh or frozen berries. If using frozen berries, just make sure to let them defrost before making the batter.