Remove flowerets from broccoli and cut into 1-inch pieces. Cut stems crosswise into 1/2-inch thick slices. Steam broccoli 3 minutes, or until tender crisp. Let cool slightly.
Preheat oven to 350˚F.
In large bowl, mix together Cheddar cheese, yogurt, and ricotta. Gently stir in broccoli.
Evenly spread broccoli mixture into lightly greased 13x9-inch baking pan. The larger pan will create a thin layer of broccoli with lots of delicious topping.
In small bowl, combine together panko, olive oil and salt. Sprinkle evenly over broccoli mixture.
Bake 20 minutes. If topping is not browned enough, increase oven temperature to 425˚F and move pan to top rack. Bake 1 to 2 minutes longer, or until topping is golden brown and crisp, watching carefully so topping does not burn.