Preheat the oven to 350°F.
In a large skillet over medium heat, add the oats and butter and toast the oats for about eight minutes until they turn golden brown. Stir often while toasting.
Add the toasted oats to a food processor with a metal blade and process for about 30 seconds, or until the oats are ground into a coarse meal.
Add flour, salt, baking powder, and baking soda to the oats in the food processor and pulse until everything is mixed well.
In a large bowl, mix brown sugar and melted butter thoroughly. Add milk and eggs, then blend everything together. Stir in the flour and whisk until smooth. Let it sit for 20 minutes so the oat flour can absorb the liquids.
While the muffin batter rests, prepare the muffin topping by mixing oats, flour, toasted pecans, cinnamon, butter, brown sugar, and a pinch of salt.
Spray a 12-cup muffin pan with non-stick baking spray that contains flour, or line the cups with muffin paper liners. Use an extra-large, half-inch ice cream scoop to fill each muffin cup to the brim. Then, sprinkle about two tablespoons of the topping on top of the batter in each cup.
Bake the muffins for about 25 minutes or until they're fully cooked.
Remove from the oven and let the muffins cool on a wire rack for about 10 minutes. Then, take them out of the pan and allow them to cool for another 20-30 minutes. Serve and enjoy!