Preheat oven to 350 degrees. Line a 9x9 pan with parchment paper with overhanging sides. Spray with nonstick cooking spray. Set aside.
In a small bowl, whisk together flour, cocoa and salt. Set aside.
In a medium saucepan, combine unsalted butter and chocolate and cook over medium heat until melted and smooth, stirring often. Remove from heat and let cool for 10-15 minutes. Stir in the sugar, eggs and vanilla extract until well combined. Add the flour mixture and stir until just combined. Pour into the prepared pan and smooth the top with an offset spatula. Bake for 20 minutes. Remove from oven to wire rack. Let cool completely.
In a large bowl, whisk together sweetened condensed milk, vanilla and mint extracts and green food coloring until you reach desired color.
In the bowl of a stand mixer fitted with whisk attachment, beat whipping cream until soft peaks form. Fold the whipping cream into the sweetened condensed milk mixture until well combined. Add the chopped chocolate. Pour the ice cream over the cooled brownie crust. Use an offset spatula to smooth the top, then sprinkle with a mixture of green and white sprinkles.
Freeze for about 45 minutes and then insert sticks all the way down through the brownie layer to make 16 individual popsicles. I just glide a sharp knife over the top of the ice cream to outline the 16 popsicles and then I insert the stick into the middle of each square. When finished, return to the freezer until fully frozen.
Remove from the freezer and using the overhangs, life the popsicles from the pan. Cut the ice cream into 16 popsicles. Store in freezer.