Fudge:
Line the bottom of a 9×9-inch square pan with parchment paper and set aside.
In the bowl of a stand mixer, cream the butter, sugar, and vanilla extract until smooth and well combined.
Place the flour in a microwave-safe bowl and heat for 1 minute. Stir, then microwave again for 15 seconds, stirring once more. Allow the flour to cool slightly.
Add the microwaved flour to the butter mixture and blend until fully incorporated.
In another microwave-safe bowl, combine the sweetened condensed milk and melted white chocolate. Microwave in 15-second intervals, stirring until smooth and creamy.
Pour the melted milk and white chocolate mixture into the butter and flour mixture. Blend until fully combined, scraping down the sides of the mixing bowl as needed.
Add the blueberries to the mixture and blend on low for just a few turns to keep the blueberries intact.
Add the blue food coloring gel and mix on low, just enough to swirl the color through the fudge. Repeat with the purple food coloring, mixing briefly to create a swirl effect.
Pour the fudge mixture into the prepared pan and spread it evenly with a spatula or spoon.
For best results, refrigerate the fudge overnight to allow it to set properly.
Topping:
11. While the fudge sets, prepare the topping by mixing the oatmeal, brown sugar, vanilla extract, and honey in a small bowl until well combined.
12. Once the fudge has set, sprinkle the topping over the fudge and press lightly to adhere. Add extra blueberries if desired for garnish.