Preheat the oven to 170C/325F and grease the bundt pan. Beat the softened butter with sugar until creamy on medium speed, add the ricotta and beat until well combined.
Add the eggs and vanilla and beat for a minute longer until well blended. Then add sifted flour with baking powder, baking soda and salt, mix with an electric mixer for another minute, then add lemon juice and zest, mix briefly and pour into the prepared bundt pan.
Bake for 55-60 minutes or until a tooth pick inserted in the middle of the came comes out clean and the cake is golden.
Take the cake out of the oven, let it cool in the pan for 20 minutes then turn it out on a wire rack and let it cool completely. Once cooled brush with the blackberry glaze.
For the Blackberry Glaze
Mash the blackberries with a fork, then put them through a fine sieve. Reserve the juice and discard the pulp.
In a medium bowl combine the blackberry juice with icing sugar and boiling water, stir until the sugar is dissolved and the glaze is smooth.