Pre-heat oven to 400ºF. Prepare muffin tray with 12 paper liners.
Mix the dry ingredients in a large bowl. Combine the wet ingredients and mix well. Add the wet ingredients to the dry, and stir until just incorporated. Stir in the rhubarb pieces. Scoop the batter into the 12 muffin liners (an ice cream scoop helps you distribute the batter evenly). Bake for 23 to 25 minutes, or until the tops are nicely browned and a toothpick inserted into a muffin comes out clean.
Serve warm with butter if you prefer, but these are beautifully moist and good to eat just as they are. Or, serve with some rhubarb compote (see below for a quick “cheater” version).