Browning The Butter For The Muffins

1. Chop the butter into a few chunks and add to a small saucepan warming over medium - medium high heat.
   Slowly whisk or swirl the butter until it begins to turn a warm chestnut color and tiny brown flecks start to form on the bottom of the pan. It will take a few minutes and this is a delicate process, so stay vigilant. You want the butter browned but not burnt. Just before it's ready the butter will start to foam up.
   Remove from heat and set aside to cool.

Streusel Topping

1. Whisk together the oats, flour, brown sugar, cinnamon and salt. Then cut in the cubed butter with a pastry blender or by squishing the butter into the dry ingredient between your fingers, until coarse crumbs the size of peas form. Chill in the fridge while you prepare the muffins.

Apple Cider Oat Muffins

1. Preheat oven to 350° F. Line a muffin tin with paper liners, or lightly grease with butter.
2. Whisk the flour, oats, baking powder, baking soda, cinnamon and salt together in a mixing bowl. 
3. In a medium sized mixing bowl, add the eggs and gently whisk. Then add the cooled browned butter, brown sugar, Greek yogurt, and apple cider together. Whisk until smooth. 
4. Make a well in the center of the dry ingredients. Add half of the wet ingredients into the dry and fold together with a spatula. Add the second addition of wet ingredients an fold until just incorporated. Then gently fold in the chopped apples.
5. Use a cookie scoop to fill the lined muffin tins, filling each cup almost to the top. Then sprinkle with the Streusel Topping. 
6. Place on middle rack of oven and bake 20-25 minutes, rotating from front to back halfway through. When they are ready, the muffins will be golden brown and nicely domed. A skewer inserted in the center of one should come out clean.
7. After they've cooled for about 5 minutes in the muffin tin, carefully transfer the muffins to a cooling rack to finishing cooling. 

Apple Cider Glaze

1. Sift the powdered sugar into a mixing bowl. Add 2 tablespoons of apple cider and whisk until smooth. The glaze should run off of the whisk in a thick flowing ribbon. If the glaze is too thin, slowly whisk in more powdered sugar. If the glaze is too thick, slowly add more apple cider water.
2. Once the muffins have cooled, drizzle the glaze over the muffins and serve.