Preheat oven to 375 degrees. Line a 12 cup muffin tin with liners or spray with non-stick cooking spray.
To make the muffins, whisk together the flour, 1/2 cup of sugar, baking powder, and salt in a large bowl. Set aside.
In a small bowl, whisk together the buttermilk, cocoa, food coloring, oil, and egg.
Stir the wet ingredients into the dry until just moistened.
Beat together the cream cheese and remaining 1/4 cup of sugar in a small bowl. Fold into the muffin batter, leaving some streaks and not overmixing.
Fill the muffin tins two-thirds full with batter.
To make the crumb topping, stir together the sugar and flour in a small bowl. Use a pastry cutter to blend in the butter until you have coarse crumbs.
Sprinkle the topping over the muffins and bake for 17 to 20 minutes or until a tester comes out clean.
Cool in the pan for 10 minutes and then remove to a rack to cool completely.