You will need a large (16-ounce) glass mug for this cocktail. To garnish your glass mug, add the ¼ cup milk to a shallow dish. In a separate shallow dish, stir together the granulated sugar and cinnamon. Dip the top rim of the mug into the milk, then into the cinnamon sugar mixture. Set aside.

Add the whole milk to a microwave-safe bowl with a pour spout (a 2-cup glass liquid measure cup works well) and microwave for 1½-2 minutes. Add the white chocolate hot cocoa powder mix to the warm milk and whisk to dissolve the white chocolate cocoa powder fully.

Add the RumChata cream liqueur and Fireball cinnamon whisky to the warm white hot chocolate. Whisk to combine fully.

Carefully pour the cinnamon toast crunch cocktail into the cinnamon sugar-rimmed glass mug.

Squirt a generous amount of the whipped topping onto the cocktail and sprinkle a few of the cinnamon toast crunch cereal pieces onto the top of the whipped topping.