Rhubarb Streusel Muffins

Ingredients

• 1 cup granulated sugar
• 3/4 cup all-purpose flour
• 1 tablespoon baking powder
• 1/2 teaspoon cinnamon
• 1/4 teaspoon salt
• 1/2 cup butter (melted)
• 1 cup sour cream (or plain Greek yogurt)
• 1/4 cup milk
• 2 large eggs (room temperature)
• 1 1/2 teaspoons vanilla extract
• 2 1/2 cups diced rhubarb
• 3 tablespoons brown sugar
• 3 tablespoons butter (melted)
• 3 cups all-purpose flour
• 1/4 cup brown sugar