Preheat oven to 350°F
Spray a 15-cup bundt pan with nonstick spray
Prepare the strawberry cake batter according to package instructions. Pour into the bundt pan and gently tap to level
In a blender, combine eggs, milk, condensed milk, cream cheese, and vanilla. Blend until smooth
Slowly pour the flan mixture over the cake batter. Do not mix. During baking, the layers will naturally switch positions
Cover the bundt pan tightly with aluminum foil
Place the bundt pan inside a larger pan and fill with about 2 inches of hot water (water bath)
Bake for 50–60 minutes, or until a toothpick inserted comes out clean
Remove from oven and cool for 30 minutes, then refrigerate for several hours or overnight
Carefully unmold the cake onto a plate
Wash and dry the bundt pan, then lightly grease it again
Prepare the jello layer by heating 2 cups of milk with the strawberry jello, whisking until fully dissolved
Remove from heat and stir in the remaining 2 cups of milk. Let cool slightly
Place the cake back into the bundt pan. Carefully pour the jello mixture around the edges so it surrounds the cake
Pour remaining jello over the top
Refrigerate for at least 2 hours or until fully set
To unmold, gently warm the outside of the pan for a few seconds and invert onto a plate
Slice and enjoy