Line an 8x8 inch baking dish with parchment paper and mist lightly with nonstick spray.

Microwave all-purpose flour in a small heat-safe bowl for 1 minute, allow to cool, then sift to remove clumps.

Place 1 cup of semi-sweet chocolate chips into a Ziploc bag and freeze.

In a medium mixing bowl, mix the softened butter, granulated sugar, light brown sugar, milk, vanilla extract, and salt using a handheld mixer for 1.5 to 2 minutes until smooth.

Lower mixer speed and gradually add cooled flour, blending until just combined.

Melt white chocolate chips with sweetened condensed milk in a heat-safe bowl, microwaving in 30-second intervals and stirring until smooth.

Mix frozen chocolate chips into the butter mixture using a wooden spoon until combined.

Stir in the melted white chocolate mixture until fully incorporated.

Spoon the fudge mixture into the prepared baking dish, sprinkling reserved chocolate chips on top and pressing them in lightly.

Cover and refrigerate for at least 2 hours, or preferably overnight.

Once set, cut into squares and present on a delicate plate. Optionally serve with tea or coffee.