Divide the Pillsbury dough into two small loaves and bake according to package directions, subtracting five minutes from the total baking time.

Remove bread from the oven when golden brown and let cool briefly.

In a small pot, combine membrillo with 1/4 cup of water and heat over low heat until it reaches a jam-like consistency.

Slice the loaves in half lengthwise and spread each half with the quince paste.

Stack slices of ham followed by a generous layer of manchego cheese onto each piece.

Melt butter in a large skillet over medium-low heat.

Add sandwiches to the skillet and cook for a few minutes per side, applying weight as needed.

Cook until lightly browned and cheese has melted, or alternatively cook in a panini press.