• Preheat oven to 350°F.
• Mise en Place. Bring butter and eggs to room temperature (the butter should be cool, around 65°F, but soft to the touch, not melty or greasy).

  Measure sugar and orange zest into the bowl of your stand mixer.

  In another container, whisk together flour, baking powder, and salt and set aside.

  In a small bowl, whisk together 50g sour cream with 50g orange juice and orange pulp/flesh. Reserve at least a quarter of the orange with the peel on and un-juiced to make the glaze later.

  Grease an 8x4" loaf pan and line with a parchment paper sling. Set aside.
• Infuse the sugar. In the bowl of your stand mixer, use your fingers to rub the orange zest into the sugar until it is orange and fragrant.
• Cream the butter and sugar. Add the softened butter to the bowl. Beat on low speed until there's no loose sugar, then increase speed to medium and continue creaming for 3-5 minutes, pausing to scrape down the bowl and the beater at least 3 times. Properly creamed, the butter and sugar will have a fluffy, airy, and paste-like texture and pale orange color. Scrape down the sides of the bowl.
• Add eggs. One at a time, crack each egg into a small bowl (to avoid getting shells in your cake!) then dump the egg into the mixer bowl, beating on medium speed for at least 60 seconds and scraping down the bowl again before adding the next egg. Scrape down the bowl again after the last egg has been added.
• Alternate adding dry ingredients and sour cream. With the mixer running on the lowest possible speed, add half of the dry ingredients. When they are mostly combined, scrape down the bowl and beater. Add the orange sour cream mixture and mix on low just until combined, then stop and scrape the bowl and beater again. Add the remaining dry ingredients and mix on low just until just a few streaks of flour remain. Scrape down the bowl and beater and finish mixing by hand with a spatula to prevent over mixing.
• Bake. Scrape the batter into the parchment-lined loaf pan. Use a mini offset spatula to smooth out the batter, pressing it down into the corners and sides of the pan so that there aren't any trapped air bubbles. [OPTIONAL] Cut a ⅛-inch thin slice of a stick of butter into small sticks and arrange them in a line down the middle length of the pan to help control the crack in the top of the loaf as it bakes. Bake in the center of a 350°F oven for 60-65 minutes, until a toothpick inserted in the center comes out with just a few crumbs clinging to it.
• Cool. Remove the pan to a cooling rack. Let cool 10-15 minutes, then use the parchment sling to lift the cake out of the pan to finish cooling. Let cool completely before slicing.

Orange Icing Glaze

• Sift powdered sugar into a small mixing bowl. Add orange zest and juice. Whisk together until smooth. Add more juice to thin it out or more powdered sugar to thicken it.
• Use a mini offset spatula to spread the glaze over the top of the loaf cake. Let sit to form a crust or serve immediately!