Preheat oven to 350°F.
Grease a loaf pan and line with a parchment sling. Set aside.
In a large bowl combine flour, baking powder, baking soda, salt, cardamom and grapefruit zest. Mix to combine and set aside.
In a medium bowl whisk together eggs, yogurt and sugar. Gently pour in ½ cup grapefruit juice, milk and cooled butter. Gently stir together.
Pour wet ingredients into the bowl of dry ingredients. Use a rubber spatula to gently combine. Avoid over-mixing the batter.
Pour cake batter into prepared pan.
Bake for 25-35 minutes, or until inserted toothpick comes out with little crumbs.
Allow cake to cool in pan for 20 minutes before removing.
Make the glaze while cake is cooling: Combine powdered sugar, grapefruit juice and vanilla in a small bowl and whisk until smooth.
Once cake has cooled, remove from the pan and place a cooling rack.
Place a baking sheet under cooling rack to catch glaze. Pour glaze over cake.
Once glaze has set, slice, serve, and enjoy! Recipe from fitmittenkitchen.