Using browned butter requires you to form an emulsion by whisking starchy pasta water with butter until you achieve a uniform sauce. If you’re not boiling batch after batch of pasta, your water may not be starchy enough. Please add 1 tablespoon semolina flour per quart of water to achieve the right starch content in your pasta water. Make this addition when you add the pasta to the water. If you do it sooner, your water will boil over if you’re not attentive.