STEP 1: Put white chocolate chips, sweetened condensed milk, and butter in a large melting pot or saucepan. Warm gently over medium-low heat stirring constantly.

STEP 2: Pour ⅓ of the mixture into the prepared baking pan.

STEP 3: Spoon ⅓ of the berry sauce around the top of the mixture in the pan and then swirl it around in the fudge mixture with a knife.

STEP 4: Repeat with another third and then the final third.

STEP 5: Place fudge in the fridge for at least 2 hours, or until totally set.

STEP 6: Remove from the refrigerator and remove the fudge from the pan. Slice the fudge into squares and serve.

STEP 1: Cook the berries, sugar, water, lemon zest, and lemon juice in a saucepan over medium heat while stirring continuously until berries break down and sugar is thoroughly dissolved (5-10 minutes).

STEP 2: Press the sauce through a fine-mesh strainer into a mixing bowl to remove seeds.

STEP 3: Mix the cornstarch and lemon juice together, then mix it into the sauce. The sauce will thicken into a glossy syrup almost instantly. If for any reason your sauce doesn’t thicken, add more cornstarch.

STEP 4: Cool the sauce to room temperature.

STEP 5: Cover the sauce with a lid or plastic wrap and refrigerate for at least 45 minutes to thoroughly chill.