In a mixer bowl beat the sour cream until smooth, drizzle in the sweetened condensed milk until combined.

Add the lemon juice and mix thoroughly.

In a small bowl combine the graham cracker crumbs with the butter until it resembles coarse crumbs.

Cut the marshmallows with scissors into slices (add powdered sugar if they are very sticky and stick to your scissors)

In an 8-inch loaf pan:

layer the ice cream mixture then add a tablespoon of graham cracker crumbs on top and marshmallow pieces.

Repeat layers.

Freeze for 5-6 hours