Line an 8x8 baking dish with parchment paper. Be sure to have an overhang on 2 sides to help lift the fudge out of the baking dish. Lightly spray the parchment paper with nonstick cooking spray to keep the fudge from sticking to the parchment paper. Set it aside
Add the frozen blueberries, sugar, lemon juice, and cornstarch to a 1 to 2-quart heavy-bottomed saucepan over medium low heat. Bring the mixture to a low simmer, stirring constantly to break up the berries until the mixture thickens to a really thick canned pie filling consistency. This should take about 8-10 minutes.
½ cup frozen blueberries, 2 tablespoons granulated sugar, 1 tablespoon freshly squeezed lemon juice, 1½ teaspoons cornstarch
Place a fine-mesh strainer over a medium-sized bowl. Add the blueberry mixture to the strainer. Use a silicone spatula to mash the blueberry topping through the strainer. (Be sure to scrap the blueberry topping that clings to the bottom of the strainer) Once you have extracted all the strained and thickened blueberry topping, discard the berry hulls. Cover and chill in the refrigerator for 1 hour.
Add the white baking chips to a medium size microwave-safe bowl. Microwave on high power for 1 minute, stir and continue heating in 30-second intervals. Continue to stir well after each interval until the chocolate is melted and smooth. (Be careful not to overheat the chocolate chips as this will result in a grainy texture)
3 cups white baking chips
Add the sweetened condensed milk to a small microwave safe bowl and heat in the microwave for 45 seconds to 1 minute or until warm, but not boiling.
1 cup sweetened condensed milk
Stir in the heated sweetened condensed milk to the melted chocolate. (The mixture will seem somewhat grainy at first, but it will smooth out)
Add the thickened blueberry topping (do not stir the blueberry topping before adding to the white chocolate) to the white chocolate mixture and gently fold in no more than 3 times. (You are wanting to create a marbled appearance) Immediately pour the white chocolate fudge base into the lined 8x8 baking dish. Cover with plastic wrap or aluminum foil and chill in the refrigerator for 3-4 hours, or until the chocolate is set.
Once set, use the parchment paper overhang to lift the fudge out of the baking dish. Using a sharp knife, carefully slice 6 slices x 6 slices. Keep the fudge in the refrigerator until ready to serve.
Video
Notes
Storage:
To Store: Store any leftover fudge in an airtight container in the refrigerator for up to 7 days.
To Freeze: You can freeze the fudge for up to 2 months. Wrap the fudge in waxed paper and then in a gallon-size ziplock bag. Allow the fudge to thaw overnight in the refrigerator before serving.
Tips:
Be sure you use sweetened and not evaporated milk. Your fudge will not set if you use evaporated milk.
You can substitute other berry pie fillings for the blueberry filling.
If you choose to freeze the fudge, I do recommend leaving the fudge whole and not sliced. The fruit can “bleed” when defrosting.
When preparing your pan with parchment paper, be sure to have an overhang on 2 sides to help lift the fudge out.