Preheat oven to 350°F (180°C). Line a 9-inch (23cm) springform with detachable sides with parchment paper in the bottom and grease the sides.

For the brownie bottom:

1. In a medium sized bowl, combine butter, sugar and vanilla extract. Add the eggs and mix until well combined.
2. In another bowl, combine flour, cocoa, baking powder and salt.
3. Add the dry ingredients to the egg mixture and mix until well combined.
4. Pour the batter into the prepared pan and spread evenly. Bake for 20-25 minutes, or until a toothpick comes out clean.

For the white chocolate cheesecake:

1. Place a baking pan filled with hot water on the lower rack of the oven. Preheat oven to 325°F (160°C).
2. In a metal bowl over a pan of simmering water, melt white chocolate chips with the whipping cream, stirring occasionally until smooth. Alternately, white chocolate can be melted in the microwave with the whipping cream in a glass bowl, at 50% power, stirring every 30-60 seconds until smooth.
3. In a large bowl, beat softened cream cheese and sugar with an electric mixer until smooth. Blend in flour. With mixer on low speed, blend in eggs one at a time. Blend in vanilla and melted white chocolate.
4. Pour the cheesecake batter over crust and bake for 55 to 60 minutes, or until filling is set. Cool, cover with plastic wrap, and refrigerate for 8 hours before removing from pan.
5. Just before serving, mix sliced strawberries in a bowl with lime zest and juice. Drain the excess of juice, then display the strawberries on top of the cheesecake, decorating with fresh mint leaves.