Heat oven to 350 degrees Fahrenheit.

Heat butter in a pot, until melted. Add in the flour and whisk until clumps form. Slowly pour in the milk while whisking. Continue whisking as the milk comes to a simmer. Cook for one minute, until the sauce has thickened and coats the back of a spoon. Turn off the heat and stir in the parmesan cheese and broccoli florets. Set aside.

Place the blintzes in a single layer on the bottom of a nine- x 13-inch pan. Pour the sauce over the blintzes. Cover and bake for 30 minutes. Uncover and bake for an additional 10 minutes. Broil for two to three minutes if desired.