Preheat your oven: Start by preheating your oven to 350°F (175°C) and prepare a muffin tin by greasing it or lining it with paper cups.
Mix the wet ingredients: In a mixing bowl, whisk together the granulated sugar, brown sugar, vegetable oil, milk, and eggs until well combined.
Combine dry ingredients: In another bowl, mix the all-purpose flour, baking powder, and salt.
Combine mixtures: Gradually add the dry ingredients to the wet bowl, stirring gently until just combined. Avoid overmixing to keep the muffins tender.
Add rhubarb and vanilla: Gently fold in chopped rhubarb and vanilla extract, ensuring it is evenly distributed throughout the batter.
Fill the muffin tin: Fill each muffin cup about 2/3 full with the prepared batter.
Bake: Place the muffin tin in the preheated oven and bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Cool: Let the muffins cool in the tin for a few minutes before transferring them to a wire rack to cool completely.