Preheat the oven to 375°F. Coat a 12-cup muffin tin with nonstick cooking spray. Line each cup with the ham slices, pressing into the bottom and up the sides, overlapping each slice as needed. Cook the macaroni according to the package's directions and drain. Meanwhile, heat the milk in a saucepan until bubbles form around the edges. Add the Velveeta and stir until smooth, then add the cheddar and stir until smooth. Remove from the heat and fold in the pasta and peas. Divide among the muffin cups and sprinkle the cheese straws on top. Bake until the cheese is bubbling and the edges and top are brown, about 10 minutes. Remove from the muffin tin and serve hot.