Preheat the oven to 400 degrees. Coat a muffin tray with cooking spray.
Combine the sugar with the blood orange zest together in a bowl with your fingertips until the sugar is moist and the blood orange fragrance is strong. Mix the flour, baking powder, baking soda, and salt together in a separate bowl until well combined.
Beat the sour cream, blood orange juice, eggs, vanilla extract, softened butter, and blood orange sugar together in a bowl with a mixer until creamy and smooth. Slowly combine the flour mixture with the sour cream mixture. Add the poppy seeds and mix well.
Scoop the batter evenly into the muffin cups in the tray.
Place into the oven and cook for 16-18 minutes, or until a tester inserted in the center comes out clean. Let the muffins cool on a rack before serving. Enjoy.