Spray an 8-inch square casserole dish with nonstick cooking spray. Line with parchment paper and spritz the paper with more nonstick cooking spray.
Place the flour in a microwave-safe bowl and heat about 1 minute in the microwave or until the flour reaches 165 degrees.
Meanwhile, in a large mixing bowl, beat the butter, sugar, and vanilla until completely smooth.
Add the flour and salt to the butter mixture, beating again until combined.
Stir in 1 cup of mini semi-sweetened chocolate chips.
In a large, microwave-safe bowl, melt the white chocolate chips on high heat in the microwave, stirring after 30 seconds and then repeating for 10-second intervals.
Stir well between each session as the chocolate will continue to melt with the residual heat in the bowl. Do not overheat the chocolate as it will seize up.
Add the sweetened condensed milk to the melted white chocolate and stir well. If the chocolate cools, microwave again for 15 to 30 seconds or just until mixable.
Mix the melted chocolate and condensed milk mixture into the cookie dough mixture.
Transfer the fudge into the prepared pan.
Sprinkle remaining mini semi-sweet chocolate chips over the top and press down gently.
Refrigerate the fudge for 2 hours or until firm.
Remove the fudge from the baking dish by lifting the edges of parchment paper.
Heat a large knife under hot running water. Wipe dry and cut the fudge into squares, reheating and drying the knife between cuts.