Preheat oven to 350℉. Butter and flour a loaf pan.
Pour the 1/8 cup of blood orange juice into a glass measuring cup, then top with buttermilk until you reach 1/2 cup. Stir in the orange zest, orange extract, and vanilla extract. Set aside.
Mix together the flour, baking soda, baking powder, and salt.
In a large bowl, cream the butter and sugar together until fluffy, then beat in the eggs. Stir in half of the dry ingredients to the butter-sugar mixture, then the juice-buttermilk mixture, then remaining dry ingredients. Be careful not to overmix. Transfer the batter to the prepared loaf pan, and bake for 55-60 minutes, until a cake tester comes out clean. Cool 10 minutes in the pan, then turn onto a wire rack.
Whisk together the confectioners’ sugar and remaining 2 tablespoons blood orange juice until smooth. Pour glaze over the cooled cake. Slice and serve.