Prepare the Pan:
Line a 9×9-inch baking dish with parchment paper, making sure it covers all sides. Lightly spray with nonstick cooking spray. Set aside.

Mix Flavor & Color:
In a small glass bowl, combine banana flavoring and yellow food color gel. Stir until smooth and set aside.

Heat the Base Mixture:
In a heavy-bottomed 3–4 quart saucepan over medium heat, combine butter, half and half, heavy cream, and clear vanilla flavoring. Stir continuously until the butter is fully melted.

Add Sugar & Simmer:
Stir in granulated sugar. Continue stirring as the mixture reaches a simmer (about 6–7 minutes). Let it simmer for an additional 3 minutes while stirring constantly. Remove from heat.

Melt the White Chips:
Add white baking chips to the hot mixture, cover, and let sit for 3–4 minutes. Stir until the chips are completely melted and smooth.

Incorporate Marshmallow Fluff:
Add marshmallow fluff to the mixture and stir until fully blended.

Add Banana Flavoring & Color:
Stir in the prepared banana flavor and food gel mixture until evenly colored and smooth.

Set the Fudge:
Spread the fudge evenly into the prepared baking dish using a silicone or offset spatula. Sprinkle crushed Nilla wafers on top (if desired). Cover with aluminum foil.

Chill to Set:
Let the fudge rest at room temperature for 30 minutes, then refrigerate for at least 4 hours.

Cut & Serve:
Once firm, lift the fudge out of the pan using the parchment paper. Cut into 25 even squares (5×5). Store in the refrigerator until ready to serve.