Preparation of Streusel Topping: In a small mixing bowl, combine 1/3 cup of all-purpose flour, 1/3 cup of granulated sugar, and 1/2 teaspoon of ground cinnamon. Integrate the cold, unsalted butter into the mixture, employing a hand-mixing technique until the mixture reaches a crumbly consistency. Set aside for later use.
Muffin Batter Preparation: Begin by preheating the oven to 375 degrees Fahrenheit. Prepare a large muffin pan by lining it with 12 muffin paper liners.
Dry Ingredients Mixture: In a large bowl, mix together 2 cups of all-purpose flour, 1 cup of granulated sugar, 1 teaspoon of ground cinnamon, 2 teaspoons of baking powder, 1 teaspoon of baking soda, and 1/2 teaspoon of salt. Incorporate the diced peaches into this mixture, reserving approximately 3/4 cup for later use as a topping.
Wet Ingredients Mixture: In a medium-sized bowl, whisk together 2 large eggs, 1/3 cup of yogurt, and 1/3 cup of oil (vegetable, olive, or canola). Gently fold this mixture into the dry ingredients until just combined.
Assembling the Muffins: Evenly distribute the muffin batter into the prepared muffin cups, filling each approximately three-quarters full. Top each muffin with the reserved peach pieces and a spoonful of the previously prepared streusel topping.
Baking Process: Place the muffin pan in the preheated oven and bake for approximately 18 to 20 minutes, or until the muffins achieve a golden-brown coloration and a toothpick inserted into the center of a muffin comes out clean.
Cooling and Serving: After baking, remove the muffins from the oven and transfer them to a cooling rack. These muffins can be served either warm or at room temperature for optimal taste and texture.