Make Brownie Layer

1. Preheat oven to 290º
2. Line a 9" square baking pan with vegetable oil or butter, or line with parchement paper that is cut longer than needed (to use to lift the finished bars out of the pan)
3. Melt the chocolate and butter together in the top of a double boiler placed over simmering water. Let the mixture cool for 5 minutes
4. Add sugar, melted chocolate and butter to a medium-sized mixing bowl and beat on medium-high speed until blended
5. Add eggs and beat until mixture is blended, scraping down the sides of the bowl
6. Add flour and mix until combined. Be sure to scrape down the bowl again, and use a spatula to incorporate any flour on the bottom of the mixing bowl
7. Spread the chocolate batter evenly in the prepared pan (it helps to use an offset spatula dipped in warm water). Freeze 10 minutes while you prepare the second layer

Make Cheesecake Layer

1. Add cream cheese, eggs, sugar and lemon juice in a food processor and process until smooth (about 1 minute). Stop the machine once to scrape the bowl

Assemble & Bake

1. Remove the pan from the freezer. Carefully spoon the cheesecake mixture over the brownie layer (again, using an offset spatula dipped in warm water is helpful!) and spread it gently over the brownie, careful not to mix the two together
2. Bake until the top is set and the center is just about level with the sides, about 45 minutes
3. Let the brownies cool in the pan on a rack for 1 hour. If you lined with parchment paper, lift the bars out of the pan using the sides of the parchement. Cut into squares with a thin, sharp knife, dipping the knife in hot water and wiping it off after each cut. Serve as-is, or garnish with fresh berries