For the streusel topping, combine melted butter, brown sugar, granulated sugar, flour, and cinnamon with a rubber spatula until it forms crumbles. Set in the fridge to chill.
For the Muffins
Rinse, peel, then dice two honeycrisp apples.
In a large mixing bowl, whisk together the eggs, light brown sugar, granulated sugar, vanilla paste, oil, milk, and cinnamon until well combined and the cinnamon is distributed.
Add the flour, baking soda, baking powder to the wet ingredients then fold together with a spatula.
Once the majority of the flour is mixed in, pour in the apples and gently fold in until the apples are fully incorporated. Let sit on the counter for 10 minutes.
Preheat the oven to 375º. Using a large cookie scoop, scoop the batter and add to the muffin tin, leaving space between each muffin. Top with a generous serving of streusel, then bake for 23 minutes. Let cool for 10 minutes before removing.
Notes
Switch from the whisk when mixing the batter to a spatula as you fold in the flour. After trial and error, and lots of revamping and recipe writing, this yields an airy texture and less chewy, as a whisk is intended to whisk volume to the eggs, and over-whisking or mixing can cause the batter to get gummy.Let the muffin batter sit on the counter for an extended period of time. When the batter rests, it gives the leavening agents (baking soda, baking powder) to marry and build up so that when the muffins bake, it'll aid with the texture, mouthfeel, and overall rise.Leave room in between the muffins in the muffin tin itself. That might mean using more than one muffin tin to bake with. This gives the muffins some room to rise up higher and fluffier when they bake.USE A SCALE! I highly recommend investing in a good quality scale. Measuring in grams versus a regular measuring cup yields such different and varying results when you bake. Baking is science, so using a scale will give accurate measurements every single time.