Preheat the oven to 400 degrees F.
Unwrap the phyllo and remove 5 sheets from the stack. Reserve the remaining dough for another use.
Put a round baking pan on top of the phyllo sheets and trim the sides. Lay the phyllo circles flat between 2 damp kitchen towels. Set the pan aside.
Lay down 1 piece of phyllo dough on your work surface. Brush with butter and sprinkle with ground pistachios. Put a second phyllo sheet on top of the first and brush with butter and sprinkle with pistachios. Repeat 3 times, making 5 layers and the top being only phyllo. Put the stacked dough into the baking pan. Alternately, cut into squares 2 inches larger than muffin cup size; lightly butter the muffin tin and gently press prepared phyllo squares into each muffin cup to form small bowl shapes.
Recipe courtesy of Claire Robinson, 2010