Preheat & Prep: Preheat your oven to 350°F. Line a muffin pan with liners.
Make the Crumb Topping: In a bowl, melt the butter. Stir in flour, cinnamon, and sugars, mixing with a fork until pea-sized crumbs form. Set aside.
Prepare the Batter: In a mixing bowl, whisk together milk, vinegar, Greek yogurt, oil, vanilla extract, and eggs. Stir in the sugar until well combined.
Add the Tea Flavor: Cut open a vanilla chai tea bag and scoop out ½ tsp of the tea leaves. Mix them into the batter.
Incorporate Dry Ingredients: Mix in the flour and baking powder until smooth and lump-free.
Fill & Top: Pour the batter into muffin liners, filling them about ¾ full. Sprinkle the crumb topping generously over each muffin.
Bake: Bake for 22-25 minutes or until a toothpick inserted in the center comes out clean.
Optional Glaze: While muffins cool, whisk together melted butter, powdered sugar, heavy cream, and vanilla extract. Drizzle over cooled muffins.