01 - Preheat oven to 400°F. Line a 12-cup muffin tin with paper liners or grease each well thoroughly.
02 - In a large bowl, whisk together the all-purpose flour, baking powder, baking soda, salt, and granulated sugar until evenly distributed.
03 - Fold the shredded cheddar cheese and finely diced jalapeños into the flour mixture until evenly coated.
04 - In a separate bowl, combine the brewed sweet tea, buttermilk, melted butter, and egg. Whisk until the mixture is smooth.
05 - Pour wet ingredients into the dry mixture. Using a spatula, gently mix until just combined; avoid overmixing to maintain fluffiness.
06 - Divide batter evenly among muffin cups, filling each about three-quarters full.
07 - Bake for 18 to 20 minutes until tops are golden and a toothpick inserted into the center emerges clean.
08 - Allow muffins to cool in the pan for 5 minutes, then transfer to a wire rack. Serve warm or at room temperature.