Step 1

Preheat the oven to 350 degrees F and line two 12-cup muffin tins with liners or grease the cups with cooking spray.

Step 2

In a large bowl, whisk together the flour, baking soda, baking powder, and salt. Toss in the chopped rhubarb and stir to coat.

Step 3

In a medium bowl or large liquid measuring cup, whisk together the brown sugar, oil, egg, vanilla and buttermilk until smooth.

Step 4

Make a well in the center of the dry ingredients and pour in the wet ingredients. Stir just until combined. Don't overmix!

Step 5

Divide the batter evenly among the muffin cups.

Step 6

In a small bowl, stir together the streusel ingredients with a fork until crumbly and combined. Sprinkle a little bit (about a teaspoon or so) of the streusel on top of each muffin.

Step 7

Bake for 16-20 minutes until the tops of the muffins spring back to the touch and/or a toothpick inserted in the center comes out clean. Don't overbake or the muffins may be dry.

Step 8

Let the muffins cool for five or so minutes before removing them from the pan to cool completely on a wire rack. These muffins keep great covered at room temperature for several days.