A New York-style crumb cake is given a subtle technical tweak (extra sour cream and a thicker crumb topping) to produce a reliably moist, bakery-worthy square that translates well to home kitchens.
Hasn’t it been far too long since you last had a truly perfect crumb cake? You know the kind — a substantial square with a cinnamon-brown sugar crumb layer nearly as tall as the tender, buttery cake beneath it, enriched with sour cream and a hint of vanilla. I thought I had wrapped up my personal crumb-cake quest in 2021 with the still-excellent Big Apple Crumb Cake, but this time around I realised that a true New York crumb cake needed a somewhat different approach.
It turns out the Big Apple Crumb Cake (minus the apples) wasn’t exactly the New York crumb cake I wanted. After a few adjustments — more sour cream, a splash of water or milk, and (stay calm) increasing the crumb layer thickness by about 25% — I landed on this dream of a square: almost comically top-heavy, the very sort of cake you’d stare at in a bakery window hoping that it tastes as good as it looks. I’ve baked and given this to so many people — family, my daughter’s teachers, friends on group texts pleading “Help, I made too much crumb cake!” — that by now it’s almost impossible to find someone who hasn’t tried it. Now it’s your turn.
10 tablespoons (140 grams) unsalted butter, melted
1/2 cup (110 grams) dark brown sugar
1/4 cup (50 grams) granulated sugar
1 1/4 teaspoons ground cinnamon
1/4 teaspoon kosher salt
1 2/3 cups (215 grams) all-purpose flour
6 tablespoons (85 grams) unsalted butter, softened
1/2 cup (100 grams) granulated sugar
1 large egg
1/2 cup (120 grams) sour cream
2 tablespoons (30 ml) water or milk
1 teaspoon (5 ml) vanilla extract
1 cup (130 grams) all-purpose flour
1 1/4 teaspoons baking powder
3/4 teaspoon kosher salt
Powdered sugar, for dusting
Preheat the oven to 350°F (175°C). Lightly grease an 8-inch square or 9-inch round cake pan with butter or nonstick spray. For extra safety, line the pan with parchment paper.
Whisk together the melted butter, both sugars, cinnamon, and salt until the mixture is uniform. Add the flour and stir until it is fully incorporated — the mixture will be very thick. Press it down in the bowl to compact it a little, then set it aside.
Beat the softened butter and granulated sugar until the mixture is lighter and fluffy. Add the egg, then mix in the sour cream, water (or milk), and vanilla until the batter is homogenous. Sprinkle the surface of the batter with the baking powder and salt and beat well to incorporate. Add the flour and mix only until it disappears into the batter.
Spoon the batter into the prepared pan and smooth it level. Use a spoon to loosen the crumb mixture from the bottom of the bowl, breaking it into a mix of larger chunks and smaller rubble. Distribute the crumbs evenly over the top of the batter.
Bake for about 30 to 35 minutes, or until a toothpick inserted into the cake layer just beneath the crumbs comes out clean of batter. Check in several spots in case it has baked unevenly.
Allow the cake to cool to lukewarm if you can — it’s tempting, I know — before dusting generously with powdered sugar and slicing into squares or wedges.
Stored in an airtight container at room temperature, this cake keeps for 3 to 4 days, though it’s at its best within the first two days.
