Preheat your oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment or lightly grease it.
In a medium bowl, cream together the softened butter and sugar until light and fluffy.
Beat in the eggs one at a time, then stir in 3 tablespoons of lemon juice and the food coloring, if using.
Fold in the flour gently until just combined—do not overmix.
Spread the batter into the prepared baking dish, reserving about ⅓ cup of batter for the top.
In a separate small bowl, combine the softened cream cheese and a tablespoon of sugar until smooth.
Dollop spoonfuls of cream cheese mixture onto the batter, gently swirling with a knife or skewer to create a marbled effect.
Spoon the reserved batter on top and gently smooth out if needed.
Bake for 25-30 minutes, or until the edges are set and the center is just slightly jiggly.
Allow the brownies to cool completely.
For the icing, whisk together powdered sugar and 2-3 tablespoons of lemon juice until smooth and drizzly.
Pour the icing over cooled brownies and finish with yellow sprinkles, if using. Let set, slice into squares, and enjoy!
