Crumble bulk Italian sausage into 10-oz custard cup [15-oz casserole].
Cover loosely and microwave on high (550 watts), stirring every min, until done, 2 to 3 min [3 to 4 min]; break up and drain.
Spread 1 tbsp pizza sauce over each English muffin half.
Top with sausage and remaining ingredients.
Place on plate.
Microwave uncovered on high (550 watts) until cheese is melted and bubbly, 1 to 2 min [2 to 3 min].