Rosemary Lemon Brown Butter Muffins

To brown the butter: In a saucepan set over medium heat, melt the butter. Once melted, the butter will start to sizzle and may spatter. Continue to cook the butter, swirling the pan regularly, until it’s a rich golden brown and brown bits start collecting at the bottom of the pan; the butter will have stopped sizzling and may also have a layer of foam on the surface.

Remove the pan from the heat and pour the browned butter into a heatproof bowl. Set aside to cool to room temperature, about 25 to 30 minutes on the counter.

Preheat the oven to 350°F. Lightly grease the 12 wells of a standard muffin pan or line them with cupcake papers and lightly grease the papers.

To make the topping: Using a small bowl, measure out 2 1/2 tablespoons (35g) of the brown butter and use your fingers or a spatula to gently stir in the remaining ingredients until crumbly. Place the topping in the refrigerator while you prepare the muffin batter. 

To make the batter:  Weigh your flour; or measure it by gently spooning it into a cup, then sweeping off any excess.  

In a medium bowl, combine the flour, baking soda, salt, and spices. Set aside. 

In a liquid measuring cup, mix together the buttermilk and sour cream. Set aside.

In a large bowl, combine the remaining brown butter, brown sugar, and eggs.  

Add one-third of the dry ingredients to the bowl, stirring to combine, then stir in half the buttermilk mixture. Stir in another third of the dry ingredients, the remaining buttermilk mixture, and the rest of the dry ingredients. Scape the bottom and sides of the bowl to make sure everything is thoroughly combined.

Quickly and gently fold the zest, lemon juice, and rosemary into the batter. 

Divide the batter evenly among the wells of the pan, using about 1/3 cup batter for each; a scone and muffin scoop works well here. Sprinkle the tops of the muffins with the chilled topping.

To bake the muffins: Bake the muffins until their tops are golden brown and a toothpick inserted into the center of one comes out clean, 20 to 25 minutes.

Remove the muffins from the oven and allow them to cool in the pan for 5 minutes before transferring them from the pan to a rack to cool completely. 

Store muffins, well-wrapped, at room temperature for two or three days; freeze for longer storage.