How to Make It
Lightly grease and then line a (8x8-inch or 9x9-inch) square baking pan with parchment paper, allowing a 1 ½-inch overhang on each side.
Whisk together the graham cracker crumbs, brown sugar, and salt in a medium sized bowl. Stir in the melted butter to evenly coat. Firmly press the mixture into an even layer in the bottom of the prepared pan. Place pan in the freezer while you prepare the filling.
Beat the cream cheese in a large mixing bowl at medium-high speed until fluffy, Add the powdered sugar, tequila (if using), lime zest, lime juice, orange zest, and vanilla extract to bowl; beat at medium speed until combined. Mix in a few drops of green food coloring if desired.
In a separate bowl, whip the cream (using a hand or stand mixer, fitted with a whisk attachment) until stiff peaks form. Fold the whipped cream into the cream cheese mixture. Spread in an even layer over the graham cracker crust. Cover with plastic wrap and refrigerate 8 hours or overnight.
To serve, use the parchment overhang to carefully transfer the cheesecake to a cutting board. Carefully peel the parchment paper from the sides and cut into squares. Serve immediately and refrigerate any leftovers.
Avoid freezing the cheesecake bars as doing so will yield an unpleasant, icy consistency.