Put the milk and 1 cup of the cereal in a medium bowl and let stand until the milk tastes like the cereal, about 30 minutes. Strain the flavored milk and reserve. Discard the soaked cereal.
Crush the remaining 7 cups cereal in a resealable plastic bag with a rolling pin. Add 1/2 cup of the melted butter and 2 tablespoons of the brown sugar to the bag and shake until the cereal is coated. Pack into a 9-inch springform baking pan, pressing it about 1/2 inch up the sides. Bake until lightly toasted, 12 to 15 minutes. Cool to room temperature, about 30 minutes.
Meanwhile, combine the gelatin with 1/4 cup water in a small microwave-safe bowl and set aside to soften, about 5 minutes.
Whisk together the cinnamon, remaining 4 tablespoons melted butter and remaining 10 tablespoons brown sugar in a small bowl to combine; set aside.
Beat the cream cheese, confectioners' sugar, sour cream, vanilla, salt and lemon juice in a large bowl with an electric mixer on medium-high speed until completely smooth, about 2 minutes. Scrape down the sides of the bowl and add the cereal milk. Continue to beat on low until completely incorporated, about 2 minutes.
Microwave the gelatin, stirring as needed, until melted, about 30 seconds. Add the gelatin to the cream cheese mixture and beat on medium speed to combine, about 30 seconds.
Scoop out about a quarter of the batter into another medium bowl and stir in the cinnamon-butter mixture.
Fill a 1/4-cup measure with cinnamon batter and pour into the center of the crust. Fill a 1/2-cup measure with vanilla batter and pour into the middle of the cinnamon batter. (The batter will spread; as you add alternating scoops, they will widen, forming concentric circles.) Repeat with the remaining batter, alternating between flavors and using the 1/4-cup measure for the cinnamon and the 1/2-cup measure for the vanilla, until all the batter is gone. Refrigerate until completely set, at least 4 hours and up to overnight.
Unmold the cheesecake. Pipe or dollop whipped cream around the top edge and top each dollop with a few pieces of cereal.
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