Lightly grease a standard 9×5 loaf pan and line it with a sling of parchment paper.
In a large bowl whisk together the egg, yogurt, milk, oil, brown sugar, and granulated sugar until well combined and smooth. Whisk in the baking powder and salt, then fold in the flour. Gently fold in the rhubarb. Pour the batter into the prepared pan, smoothing the top if needed.
Preheat the oven to 350℉ and let the batter rest while it heats or up to 30 minutes.
Bake for about 60 minutes, or a toothpick inserted in the center comes out just with a few moist crumbs and the top is firm when lightly touched and lightly brown.
Remove the bread from the oven and let cool for 20 minutes in the pan, then gently placed it on a wire rack to cool completely. Let the bread cool for at least 30 minutes so that the crumb firms and sets.
Notes
I used a metal baking pan, which is typically recommended when baking breads. If you use a glass loaf pan, reduce the oven temperature to 325℉.
You can add a few warming spices like cinnamon or ginger - about ½-1 teaspoon of ground spice.
Sprinkle the top with sugar - sometimes I'll sprinkle the top of this loaf with crunchy sugar or simply granulated sugar for a little added sweetness.
Storage: Keep the bread on the counter in a plastic bag or tightly wrapped in foil for up to 3 days. Store it in the fridge for up to 5 days. And, you can freeze rhubarb bread, tightly wrapped, for up to 3 months. Thaw the bread in the fridge before serving.