1 3/4 cups granulated sugar
3/4 cup packed dark brown sugar
1/2 cup heavy cream
1/4 cup milk
1 tablespoon light corn syrup
3/4 teaspoon kosher salt
2 tablespoons unsalted butter
1 teaspoon vanilla extract
1/2 cup all-purpose flour
1/3 cup mini semi-sweet chocolate chips
Coat an 8x8-inch pan with cooking spray. Set aside.
Add both sugars, the cream, milk, corn syrup and salt to a 3-qt saucepan, stirring to combine. Set over medium heat and cook, stirring occasionally, until the mixture reaches 242 F on a candy thermometer (the soft ball stage). Turn off the heat under the pan and whisk in the butter, vanilla and flour (my flour got a little lumpy and I couldn't get them all out, but it didn't wind up being a big deal).
Transfer the mixture to a 9x13 inch baking dish, and allow to cool until it reaches 110 F, about 15-20 minutes.
Using a spoon, scrape the mixture from the baking dish into the bowl of your stand mixer. Fit the mixer with the paddle attachment, and beat the fudge on medium speed for about 4 minutes, or until it thickens and holds its shape. Transfer to the prepared 8x8 pan and spread in an even layer with an offset spatula. Sprinkle with the chocolate chips and press them gently into the top of the fudge.