Mix the brown sugar and cinnamon together in a medium bowl. Stir in the melted butter, and then gently mix in the flour using a fork. Keep the mixture as large crumbles and do not over-mix. If over-mixed, this will turn into a thick paste. Set topping aside.
Prep Muffin Ingredients
Peel, core, and finely dice a large Fuji apple into small cubes. Aim for 1.5-2 cups.
In a large mixing bowl, whisk together applesauce, eggs, oil, vanilla, cinnamon, ginger, and sugar. Stir in prepped apples.
If you have a kitchen scale weigh out 240 grams of flour for most accurate results. If you don't have a scale, use the spoon and sweep method to measure out two dry cups. First fluff the flour to aerate, then gently add spoonfuls of flour to your measuring cup. Use a straight edge knife/spatula to level the flour with the top of the cup.
Add flour to a medium mixing bowl along with baking powder, baking soda, and salt. Mix well and sprinkle into the bowl with the wet ingredients.
Using a wooden spoon or silicone bowl scraper, mix until flour is incorporated, taking care not to overmix. The batter will be thick.
For extra fluffy muffins, rest the batter for 10 minutes.
While the batter rests, preheat oven to 425℉.
Ready to Bake?
For bakery-style muffin tops, line a 12-count muffin pan with 6 muffins liners, spaced so every other muffin well has batter. This will give muffin tops room to spread and rise.
If you have two muffin tins you can make all 12 muffins at once, placing both side by side on the center rack. Only have one? One pan can be baked at a time, repeating baking steps 4 and 5.
Added 1/4 cup batter per lined muffin cup, filling each one to the top of the liner. Top each with streusel crumbs.
Set a timer and bake for 5 minutes at 425ºF, then with the oven door still closed, reduce the temperature to 350ºF and bake for 15-17 minutes. Exact bake time can depend on oven temperament and type of pan used. Tops should be rounded and golden brown and an inserted toothpick will contain some crumbs, but no wet batter. Mine are perfect at the 16 minute mark with a total baking time of 21 minutes.
Let muffins sit in the pan for 10 minutes then transfer to a wire rack to fully cool.
Feel free to steal a slightly warm muffin to scarf right away - they're LEGENDARY! Leftover muffins can be stored in an airtight container on the counter for a few days and are a great grab-and-go snack option. Enjoy!
Notes
Prefer smaller muffins? You can skip the spacing of the muffins and fill each muffin cup with 3 TBSP of batter, approx 3/4 the way full. You'll end up with around 15-16 muffins Simply adjust the bake time as needed since they'll bake faster this way.Nutrition Facts below are estimated using an online recipe nutrition calculator. Adjust as needed and enjoy!