Preheat your oven to 180°C (350°F) and line a 12-cup muffin pan with paper liners.
In a large mixing bowl, combine the melted butter, granulated sugar, brown sugar, Greek yogurt, milk, eggs, vanilla extract, cinnamon, and kosher salt. Whisk until the mixture is smooth and fully combined.
Add the flour, baking soda, and baking powder to the wet mixture. Gently mix until almost combined, don’t overmix!
Add your peeled and chopped apples, and fold them into the batter just until everything is well incorporated.
Scoop the batter into the muffin liners, filling them almost to the top for tall, bakery-style muffins.
Make the crumble topping
In a medium bowl, mix together the flour, brown sugar, cinnamon, kosher salt, and melted butter. Stir until the mixture turns crumbly.
Top each muffin generously with the crumble, gently pressing it down so it sticks and doesn’t fall off while baking.
Bake in the preheated oven for 18–20 minutes, or until a toothpick inserted into the center comes out clean.
Let the muffins cool for at least 15 minutes before glazing or serving. Don’t overbake! This keeps them soft and moist!
Make a simple glaze
In a small bowl, combine powdered sugar, milk, and vanilla extract. Mix until smooth and silky. Drizzle the glaze over the cooled muffins.
Notes
Use the right apples. Go for firm and crisp apples like Granny Smith, Honeycrisp, or Pink Lady. They stay juicy and don’t turn mushy in the oven.
Weigh your ingredients. For best results, use a kitchen scale instead of cups. It gives the most accurate and consistent texture every time.
Don’t overmix the batter. Once the dry ingredients are added, mix only until just combined. Overmixing leads to dense, rubbery muffins.
Use room temperature ingredients. Eggs, yogurt, and milk at room temp mix better and help the batter rise evenly.
Peel and chop apples evenly. Chop apples into similar-sized chunks so they cook evenly and distribute well in every bite.
Don’t overfill the muffin liners. Fill each muffin cup about ¾ full to give them room to rise without spilling over.
To make this process easy, quick, and clean, use an apple peeler and corer. Here is the one I use all the time.
Don't skimp on the streusel. Be generous when sprinkling the streusel topping on each muffin. Press it gently into the batter to ensure it sticks during baking.
Cool before glazing. Let muffins cool at least 15–20 minutes before drizzling glaze. Otherwise, the glaze will melt and disappear.
Avoid overbaking! Check your muffins a few minutes before the recommended baking time. They're done when a toothpick inserted in the center comes out clean or with just a few moist crumbs.