Preheat oven to 350°F. Spray muffin tins with nonstick cooking spray; set aside.
In a medium skillet, add the ham, and onion. Cook until onions are translucent. You do not need oil because the ham provides its own oils from the fat.
1¼ cups precooked ham, 1 small onion
In a small bowl mix the mayo and half the dill together to make a sauce. Add the remaining dill to the melted butter, and mix.
½ cup mayonnaise, ½ teaspoon dill, 2 tablespoons unsalted butter
Unroll crescent dough; separate into 16 triangles. Add one triangle to each muffin tin space. Arrange the ham and onion mixture, dill mayo, and a cube or two of cheese on widest end of each triangle. Wrap the crescen dough edges together to create a ball.