Preheat your oven to 350°F and generously spray a loaf pan with nonstick cooking spray.

Whisk together in a bowl the melted butter, granulated sugar, orange zest, and Greek yogurt until well combined. Then, add the eggs one at a time, mixing gently after each addition for a smooth batter.

Combine in a separate, larger bowl the all-purpose flour, baking powder, baking soda, and kosher salt.

Mix the wet ingredients with the dry ingredients until just combined, being careful not to overmix.

Fold in the diced rhubarb gently, then transfer the mixture to your prepared loaf pan and sprinkle coarse sugar on top.

Bake for about 1 hour or until a toothpick inserted into the center comes out nearly clean.

Cool the bread in the loaf pan for 10 minutes, then transfer it to a platter to slice and serve.