Preheat the oven to 350°F (175°C).
Line a muffin tin with cupcake liners and set aside.
In a medium bowl, combine flour, cocoa powder, and salt.
In a large bowl, whisk together melted butter and granulated sugar until smooth.
Add eggs, one at a time, and mix in vanilla extract until fully combined.
Gradually add the dry ingredients to the wet mixture, stirring gently until combined.
Fold in chocolate chips, if using, to the brownie batter.
Divide the brownie batter evenly among the prepared muffin cups, filling each about halfway.
In another bowl, beat the softened cream cheese until smooth and creamy.
Add powdered sugar and lemon juice; mix until fully combined and smooth.
Carefully spoon the cheesecake mixture onto the brownie batter, filling each cup to the top.
Bake in the preheated oven for 20-25 minutes, or until the edges are set but the center is still slightly jiggly.
Let the cups cool in the tin for about 10 minutes before transferring to a wire rack to cool completely.
Top with whipped cream and your choice of toppings just before serving.
