Preheat oven to 400°F (200°C).
In a large bowl, combine all-purpose flour and salt.
Cut in cold unsalted butter until mixture resembles coarse crumbs.
Gradually add cold water, mixing until dough forms a ball.
Divide dough into 4 equal portions and roll each into a 6-inch circle on a floured surface.
Place 2 slices of deli ham on one half of each dough circle.
Top ham with 1/4 cup shredded mozzarella cheese and 2 tablespoons mild marinara sauce.
Fold dough over filling and press edges firmly to seal, creating a half-moon shape.
Place hot pockets on a baking sheet lined with parchment paper.
Bake for 25 minutes or until crust is golden brown and cheese is melted.
Allow to cool slightly before serving.