I have a question about the recipe "Brown Butter Banana Bread With Peanut Streusel" from Phyllis Grant. Could you adapt this recipe for muffins?
Sure...muffins are pretty much mini quick breads, anyway. Without having made this, I would imagine there's not enough flour for the heft that a muffin usually has. I would try bumping the flour up to 2 cups and see what kind of texture you get. Judging from the photo you may want to add another ½ t. baking powder for a bit more lift, too. But again, this is without having made the recipe before.
There should be no problem baking that in a different pan. But it's easy enough to find out. Put batter in 2 of the muffin tins for a test run and see what happens. Put a little water in all the tins that don't have batter. If you are not happy w/ the muffins, either bake off the batter in a loaf pan, per the recipe, or adjust the flour and leavener per pieceoflayercake's suggestion, and bake 2 more muffins to test. (or bake all of them if you want to be adventurous!)