Begin by preheating your oven to 350°F (175°C). This ensures that your muffins will bake evenly right from the start.

Grease your muffin pan or line it with paper liners. This will prevent the muffins from sticking and make for easier cleanup.

In a large mixing bowl, sift together the all-purpose flour, baking soda, brown sugar, and granulated sugar. This helps to aerate the flour and ensures everything combines thoroughly.

In another bowl, whisk together the egg, melted unsalted butter, buttermilk, and pure vanilla extract. Make sure the butter is not too hot; you want to avoid scrambling the egg.

Slowly pour the wet mixture into the dry ingredients, stirring gently. Mix until just combined. Over-mixing can lead to dense muffins, so be careful not to overdo it!

Gently fold in the chopped fresh rhubarb. This is where the magic happens—each piece brings its unique tang to the mix.

Spoon the batter evenly into the prepared muffin cups. Fill them about two-thirds of the way full for the best rise.

Place the muffin pan in the preheated oven and bake for about 20-25 minutes, or until a toothpick inserted in the center comes out clean. Your kitchen will fill with an enticing aroma as they bake!

Once baked, remove the muffins from the oven and let them cool in the pan for a few minutes. Then, transfer them to a wire rack to cool completely.