Preheat your oven to 350 degrees F. Lightly oil a loaf pan* (the standard size is 8.5 x 4.5 x 2.5 inches) or line with parchment paper

In a large bowl, mix together olive oil, yogurt, poppyseeds, grapefruit juice, milk, sugar, zest, and vanilla extract. Set aside. In a smaller bowl, whisk flour, baking powder, baking soda, and salt.

Carefully combine wet and dry ingredients, taking caution to not over mix but also insuring that all flour is hydrated.

Pour batter into prepared loaf pan and bake for 1 hour. Poke with a knife to check for doneness. No crumbs should stick to the knife once inserted.

Let cake cool completely in the pan. While cake is cooling, whisk ingredients for glaze in a small bowl. Drizzle on top of cake and sprinkle optional toppings, if using. Cake will keep for up to 5 days on the counter, covered.