To a 9 x 9" pan, line with parchment paper, leaving extra to fold over the sides. It is helpful to secure the paper with binder clips. Set prepared pan aside.
To a medium saucepan, add the brown sugar, sweetened condensed milk, butter, and corn syrup. Heat ingredients over medium-low heat. Using a rubber scraper, continually stir the ingredients as they melt together. Bring to a low simmer while continually stirring for 8 minutes. The mixture will resemble a thick, creamy caramel. Remove from heat and Let cool for 2-3 minutes.
Add the white chocolate chips, and stir well with a rubber scraper. Continue to stir together until the white chocolate chips melt into the caramel mixture. Mixture will be very thick and fudge-like.
Pour mixture into the prepared pan, and press evenly into pan. Sprinkle with the sea salt flakes.
Refrigerate for at least 2 hours to help the fudge set and become firm.
Once the fudge is completely firm, remove from pan by pulling the sides of the parchment paper. Transfer to a cutting board. Using a large, sharp knife, cut into lines of 8 x 8" cubes, rendering 64, 1" cubes of fudge.
Enjoy right away. Store fudge in an airtight container at room temperature. Fudge can also be frozen.
Notes
Freezing: Store fudge in an airtight freezer container or in a zip-lock freezer bag. Fudge will keep frozen for up to 2 months.