This is my southern grandma's famous peach muffin recipe. You can make them year round with frozen peaches, but they're best with fresh peaches in the summertime. The crumbly pecan-streusel topping is my favorite! Who doesn't love buttery streusel?
Heat oven to 350 degrees F. Line a 12-cup Texas-sized muffin pan with paper liners.
In a medium bowl, stir together pecans, oats, 1/4 cup flour and brown sugar until well combined; knead in butter using your fingertips or a fork, until well incorporated and mixture starts to clump together.
In a medium mixing bowl, sift together remaining 2 cups flour, baking powder and salt. In a large mixing bowl, whisk together eggs, granulated sugar, buttermilk, oil, vanilla and cinnamon until well combined. Gently stir flour mixture into egg mixture until just combined; stir in peaches.
Divide muffin batter into cups; evenly sprinkle pecan-oat mixture on top. Bake 20 minutes or until well risen, golden brown, and a toothpick inserted into muffin comes out with moist crumbs attached. Cool 5 minutes before transferring muffins to a wire rack to cool.