Beat the softened cream cheese with the dry pudding mixes in a large bowl until the mixture looks completely smooth and unified. The base should lose any cream cheese lumps before the milk goes in, which makes the final filling much silkier.

Pour in the cold milk a little at a time while mixing until a thick pudding mixture forms. By the end, it should look creamy and cohesive rather than grainy or separated.

Fold in the Cool whip or homemade whipped cream, keeping back 1/2 cup for the pan and finish. The mixture should turn light, fluffy, and spreadable, with enough body to sit in soft mounds on a spatula.

Use part of the reserved 1/2 cup to spread a very thin layer across the bottom of a 9x13 pan. This light coat helps the first graham cracker layer stay in place instead of sliding around.

Arrange 5 graham crackers across the center of the pan, then fit 2 more around the top and bottom edges, breaking them as needed. The goal is a mostly even first layer with only small gaps, so the finished slices stay tidy.

Spread part of the pudding mixture over the crackers, then scatter on a layer of blueberries and sliced strawberries. The filling should cover the crackers fully, and the berries should sit in an even layer rather than clumped in one corner.

Add another layer of graham crackers over the berries, then repeat with more pudding mixture and more berries. Press very lightly only if needed so the crackers settle without squeezing out the filling.

Repeat the graham cracker, pudding, and berry layering one more time for 3 total rounds, finishing near the top of the pan. The pan should look evenly filled, with the layers stacked level from edge to edge.

Refrigerate the cake for at least 4 hours or until the graham crackers have softened completely. When fully chilled, a gentle finger press should meet little resistance instead of a dry cracker snap.

Melt the white chocolate chips as directed on the package when you are ready to serve. The chocolate should be smooth enough to fall in thin ribbons, not thick clumps.

Drizzle the melted white chocolate over the top with a spoon or transfer it to a small zip-top bag and snip a corner for neater lines. The finish should look loose and light, so it decorates the berries without burying them.