1-Prepare the oven and muffin tin: Getting ready to bake rhubarb muffins is straightforward and fun, starting with a few basic steps that lead to tasty results. Begin by preheating your oven to 350°F and lining a 24-cup muffin tin with liners or greasing it well to avoid any sticking. This preparation sets the stage for muffins that come out just right every time.

2-Mix the wet ingredients: In a large bowl, mix the sugars, vegetable oil, buttermilk, egg, and vanilla extract until they combine smoothly this creates the wet base of your batter.

3-Combine dry ingredients and fold in rhubarb: Next, stir in the flour and baking soda just until everything comes together; be careful not to overmix for that perfect, fluffy texture. Then, fold in the diced rhubarb evenly, so its tangy flavor spreads throughout.

4-Prepare the topping and fill muffin cups: For the topping, combine the sugar, cinnamon, and softened butter in a small bowl with a fork until mixed. Fill each muffin cup about two-thirds full with batter, then sprinkle about 1 teaspoon of the topping on each one.

5-Bake and cool: Bake for 18 to 22 minutes until the muffins are cooked through, and let them cool for 15 minutes in the pan before moving to a wire rack.