Preheat the oven to 350°F (177°C) and grease a 9×5-inch loaf pan.

Whisk the flour, baking powder, and salt together in a large bowl. In a medium bowl, whisk the eggs. Once combined, whisk in the yogurt, brown sugar, oil, grapefruit juice, zest, vanilla extract, and seeds. Pour the wet ingredients into the dry ingredients and mix with a large wooden spoon or rubber spatula until combined. Avoid overmixing.

Spread batter into the prepared loaf pan. Bake for 45-50 minutes. Baking times vary, so keep an eye on yours. The cake is done when a toothpick inserted in the center comes out clean. If you find the top of the cake is browning too quickly in the oven, loosely cover it with aluminum foil.

Remove the cake from the oven and set on a wire rack. Allow to cool before drizzling with glaze.

For the glaze, simply whisk the ingredients together and drizzle over cake. Slice and serve. Cover and store leftover cake at room temperature for up to 5 days. I love it cold, so you can store it in the refrigerator too!