Melt butter in a skillet over medium-low heat. Stir the chopped pistachios into the melted butter and stir and cook until nuts begin to brown and release their fragrance, about 3 to 4 minutes. Add the breadcrumbs, stir to combine, and remove from heat.
Bring a large saucepan of water to a boil. Cook the frozen peas in the saucepan of boiling water for about 3 to 4 minutes, until heated through but still bright green. Drain peas in a colander, and return to the saucepan. Pour the pistachio-crumb mixture over the peas, mix well, and serve hot.