Line the bottom of a 9x9-inch square baking pan with parchment paper, ensuring the edges are covered for easy removal. Set aside.

In a large mixing bowl, combine the softened butter, granulated sugar, and vanilla extract. Use an electric mixer to blend until smooth and well-combined.

Place the flour in a microwave-safe bowl and heat it in the microwave for 1 minute. Stir carefully, as it will be hot. Microwave for an additional 15 seconds and stir again. Allow it to cool slightly before use.

Add the microwaved flour and salt to the butter mixture. Blend thoroughly with the mixer until a cohesive dough forms.

In a separate microwave-safe bowl, combine the sweetened condensed milk and white chocolate. Melt the mixture in 15-second intervals, stirring well between each interval, until smooth and creamy.

Gradually pour the melted white chocolate mixture into the butter and flour mixture. Use a spatula to scrape down the sides of the bowl and ensure thorough blending.

Gently fold in the fresh blueberries. If using food coloring gels, add the blue gel first and swirl lightly. Repeat the process with the purple gel, taking care not to overmix to preserve the swirled effect.

Transfer the fudge mixture into the prepared baking pan, spreading it evenly with a spatula or the back of a spoon. Refrigerate the pan overnight for optimal firmness.

Preheat the oven to 400°F (200°C). Line a cookie sheet with parchment paper. In a mixing bowl, combine the oatmeal, brown sugar, vanilla extract, and honey. Stir until the mixture is well-blended. Spread the mixture evenly on the prepared sheet.

Bake the oatmeal mixture for approximately 10 minutes, stirring occasionally to prevent burning. Remove it from the oven when golden brown, and allow it to cool completely.

Once the fudge has set, remove it from the refrigerator and cut it into 2x2-inch squares. Sprinkle the cooled oatmeal topping over each square and garnish with fresh blueberries for presentation.