Spray a 9 inch square pan with cooking spray, and line the bottom with parchment paper
In the mixing bowl of a stand mixer, mix the butter, sugar, and watermelon flavoring until smooth.
Place the flour in a microwave safe bowl, and microwave the flour until it's hot, about 1 1/2 minutes.
Add the flour and salt to the mixing bowl and mix until smooth
Melt the White Chocolate in the microwave at 10 second intervals, stirring between, until melted.
Add the sweetened condensed milk to the melted white chocolate, and stir until smooth.
Add the White Chocolate mixture to the mixing bowl, and mix on low until completely blended.
Divide 1/4 of the fudge into one bowl and the remaining fudge into another bowl.
Color the small batch green and the larger batch pink.
Pour the green fudge into a pan and press evenly into the pan with a spatula, or the back of a large spoon.
Let sit in fridge for 15 minutes, then pour the hot pink fudge on top and sprinkle with mini chocolate chips.
Refrigerate for at least 2 hours, or longer if needed, until the fudge is firm, and set. Cut fudge into 1 to 2 inch squares, and place on a plate or platter to serve.