Crumbly oat and apple muffins made with brown sugar and cinnamon. Topped with a spiced oat crumble for a crunchy bite!
These oatmeal apple crumble muffins are one of the messiest things you’ll eat and for that reason, so enjoyable: the top looks like it could be granola but in fact it’s chunky bits of cinnamon and oat streusel, inside is a soft cinnamon apple muffin punctuated by chewy bits of oats.
There’s a fairly standard formula for making muffin recipes: 2 cups flour, half a cup of butter or oil, a cup of sugar, two eggs and milk or greek yogurt. From this base line we can adapt to our needs: my first intervention was to change the sugar to brown sugar, and use buttermilk instead of plain milk. I also wanted a full grated apple in there, like I have in my apple cider banana bread and in my apple cider muffins so I altered the liquid amount to accommodate the juice the apple would bring. The apple also brings in some acidity so leavening had to be tweaked a few times to get a good rise. Lastly, I added a cup of oats, which doesn’t do too much really but it does soak up some of the liquid.
My crumble is a little non-standard too with the use of brown sugar and oats – to complement the base muffin flavors.
Butter: I use unsalted butter. For both the muffin batter and the crumble, it should be softened to room temperature. You can use salted butter but you’ll want to reduce the amount of salt added to the batter/crumble or it might be overly salty.
Sugar: brown sugar for the batter and the crumble. Light or dark.
Spices: I use cinnamon and allspice as they are deeply associated with apple pie. You can use others too if you like!
Salt: fine sea salt. If using table salt, halve the amount.
Vanilla: pure vanilla extract.
Eggs: whole large eggs. Ideally warm them a bit before adding to the batter so it doesn’t split. I set mine in a bowl of hot water for a couple of minutes.
Flour: all purpose flour of a medium protein content. If you would like to make these muffins gluten free, use a one to one flour substitute.
Leavening: a combination of baking powder and baking soda.
Buttermilk: whole or low fat. Plain kefir works too.
Oats: old fashioned rolled oats. This is important! If you use quick cooking oats or oats that are more or less broken down than rolled oats it will affect the texture of your muffins so stick to rolled.
Apple: use a baking apple like Jonagold, Granny Smith, or Honeycrisp. We’re going to shred it with a cheese grater (no need to skin it) and it’s best if you measure after grating.
Whisk together the flour, sugar, salt and spices.
Add the softened butter in sliced pats then you can use either a pastry cutter, a fork or just your fingers to work it in: the goal is to coat the flour in butter and get it into little bits.
Work it in until the streusel starts to clump, these will make nice big crumbles for the muffin topping. Set aside while you make the batter.
Set the soft butter, the sugar, spices, salt and vanilla in a bowl and use a hand mixer to beat it until it’s very well combined; it should be dark at first and turn a few shades lighter as you beat.
Add the room temperature eggs (if the eggs are cold the batter might split) and beat them in one by one. The batter will turn lighter and smooth.
Add the flour, baking soda, baking powder and buttermilk and beat just a bit – until about half combined.
Now shred the apple against a cheese grater and add it and the oats to the batter. Beat to Just combine – don’t over do it or the muffins will be tougher!
Divide the muffin batter between 12 muffin liners; use two muffin/cupcake pans and only use every other cavity so you are leaving space between every muffin. This helps them rise higher and prevents the streusel from sticking to its neighbors topping.
Sprinkle a couple of tablespoons of the streusel onto the top of the muffin batter, try to get some bigger bits – it helps if you squeeze it together in one big clump then gently break it apart on top of the batter.
Bake at 425 F for about seven minutes then lower the temperature and bake until the tops spring back or a cake tester inserted into the center comes out clean.
You can but you’ll need to change up how it’s mixed: start with the sugar, spices, salt, vanilla and eggs and beat until light and fluffy. Then, slowly add the oil (100g or ½ cup) drizzling it in as you beat. Proceed with the eggs and the rest as directed.
You can skip it and sprinkle some turbinado sugar on top for a little crunch or leave them bare.

Share & tag me on instagram @buttermilkbysam