To Make the Chunky Peach Purèe:

1. Cut the peach halves into 1/4 slices.  Add the peach slices, granulated sugar, vanilla extract, triple sec or orange juice, and kosher salt to a small saucepan.
2. Bring the mixture to a boil in a small saucepan, then reduce to low heat.  Allow the mixture to simmer for 20-25 minutes.  Stir every 2-3 minutes to check the liquid level in the bottom of the pot and to make sure that the peaches don’t stick to the saucepan.  If the liquid level is reducing too quickly (and the peaches aren’t softening), reduce the heat.
3. Once the peaches are fork-tender, use an immersion blender to blend until they form a chunky purée texture.
4. Remove from the heat and into a heat-proof bowl to cool to room temperature before using.

To Make the Muffins:

1. Preheat oven to a true 350°F (using an oven thermometer ensures that you get to the right temperature!).  Prepare a 12-cup muffin pan with muffin liners and set aside.
2. Sift the 320 g flour, 1 tsp salt, 1/2 tsp baking soda, 1/2 tsp cinnamon, and 1/8 tsp nutmeg into a medium-sized bowl.  Set aside.
3. Thoroughly combine sour cream, 135 g (~1/2 cup) cooled chunky peach puree, pure vanilla extract, and triple sec (if using) in a small bowl.  Set aside.
4. To make the streusel topping, combine the 67 g brown sugar, 32 g all-purpose flour, and 2 tbsp of cold butter in a small bowl.  Use two forks or your fingers to break the butter into pea-sized pieces and combine the rest of the mixture.  Place in the refrigerator until ready to top the muffins.
5. Place the butter into a large mixing bowl or the bowl of your stand mixer.  Mix until the butter is completely smooth.  Add the sugar and cream butter and sugar until light and fluffy.  (Need help figuring out what it means to “cream butter and sugar until light and fluffy”?  Check out this post!)
6. Add eggs, one at a time, mixing until each egg is completely incorporated.  The mixture might start to look a little curdled at this point but that’s okay in this recipe!
7. Add half of the flour mixture and mix until nearly combined.  Scrape the sides and bottom of the bowl to make sure that there is no flour at the bottom.
8. Add all of the sour cream mixture and mix until nearly combined.
9. Add the second half of the flour mixture and mix until nearly combined.
10. Finish mixing with a rubber spatula, mixing only until no streaks of flour remain.
11. Place the diced peaches and the remaining two tablespoons of flour into a small bowl.  Stir thoroughly to coat.
12. Use a sifter or fine mesh strainer to remove excess flour from the diced peaches.  We don’t want extra flour in this thick batter!
13. Gently fold the diced peaches into the batter.  Using an ice cream scoop or a 1/3 cup measuring cup, place batter into the prepared muffin cups.  Top with the refrigerated streusel topping.
14. Bake at 350°F for 25-30 minutes, or until a toothpick comes out clean.  Allow to cool in the muffin pan for three minutes, then remove to a wire cooling rack to cool completely.
15. If desired, top with The Best Vanilla Glaze after cooling for 15-20 minutes and enjoy!