Big-Crumb Streusel Topping

Before you start

Streusel made by rubbing cold butter into flour bakes into fine, sandy crumbs. For the large, craggy pieces that sit on top of a bakery coffee cake, use melted butter instead: it coats the flour and sugar evenly and lets you press the mixture into clumps that hold together in the oven. A short chill firms them so they stay distinct rather than melting into the batter.

The proportions are close to equal parts flour and brown sugar with a little less butter by weight, plus cinnamon and salt. The salt matters more than it seems; without it streusel tastes flat and sugary. Scatter the clumps on just before baking, and press them lightly so they stick without sinking.

Ingredients

• 125 g (1 cup, spooned and leveled) all-purpose flour
• 100 g (½ cup, packed) light brown sugar
• 1 tsp ground cinnamon
• ¼ tsp fine salt
• 85 g (6 tbsp) unsalted butter — melted and slightly cooled
• ½ tsp vanilla extract — optional

Method

1. Stir the flour, brown sugar, cinnamon and salt together with a fork, breaking up any lumps of brown sugar.
2. Pour in the melted butter and vanilla and stir until the mixture looks like damp sand and there is no dry flour left at the bottom of the bowl.
3. Squeeze handfuls of the mixture firmly, then break them into pieces of different sizes, from peas to small marbles. Leave a little loose crumb as well for texture.
4. Spread the clumps on a plate and refrigerate for 15 minutes, until the butter firms and the pieces feel solid.
5. Scatter the chilled streusel over the batter or filling just before it goes into the oven, then press gently so it adheres. Use about 25 g per muffin or the whole batch on a 23 cm (9 in) square cake.
6. Bake as the host recipe directs. Streusel is done when the clumps are golden brown at the edges and feel dry and crisp when tapped; if it browns before the cake is done, tent loosely with foil.

Tips for success

• For the biggest clumps, squeeze the mixture into a single ball, chill it, then tear off pieces with your fingers.
• If the streusel feels greasy and will not clump, the butter was hot. Let the mixture stand for 5 minutes and squeeze again.
• On a fruit pie, add streusel during the last 30 minutes of baking so it browns without burning.

Substitutions

Light brown sugar

Granulated sugar gives paler, crunchier crumbs with less caramel flavor. Dark brown sugar makes them softer and deeper in flavor.

Part of the flour

Replace 40 g of the flour with old-fashioned rolled oats for a chewier, more rustic topping, or with chopped pecans or walnuts for crunch.

All-purpose flour (gluten-free)

A cup-for-cup gluten-free flour blend works well because streusel needs no gluten structure. Clumps may be slightly more fragile.

Variations

Oven-toasted crumble

Spread the chilled clumps on a parchment-lined sheet and bake at 175°C (350°F) for 12 to 15 minutes, stirring once. Cool and sprinkle over yogurt, fruit or ice cream.

Cardamom-orange streusel

Replace the cinnamon with ¾ tsp ground cardamom and add the finely grated zest of 1 orange.

Troubleshooting

Streusel melted into a flat layer

The clumps were warm or too buttery. Chill them before topping, and measure the butter; 85 g is enough to bind without pooling.

Crumbs stayed pale and floury

The streusel was not baked long enough or was buried in a wet batter. Press it lightly rather than pushing it in, and bake until the edges brown.

Topping sank to the bottom of the cake

The batter was too thin or the clumps too heavy. Use smaller pieces on thin batters and add them right before the pan goes in.

Storage

Refrigerate unbaked streusel in an airtight container for up to 1 week, or freeze it for up to 3 months and use it straight from the freezer. Baked streusel softens on moist cakes after a day or two.

Safety notes

Do not eat unbaked streusel; it contains raw flour, which can carry harmful bacteria until it is baked. Contains wheat and milk.