The Very Best Brown-Butter Double-Crumb Apple Coffee Cake

• ### STREUSEL
• 115 g unsalted butter (1/2 cup), browned and cooled to opaque
• 180 g all-purpose flour (1 1/2 cups)
• 120 g light brown sugar, packed (1/2 cup + 2 Tbsp)
• 20 g granulated sugar (1 1/2 Tbsp)
• 2 tsp ground cinnamon
• 1/2 tsp fine salt
• (Optional) 60 g toasted chopped pecans or sliced almonds (1/2 cup)
• (Optional) 1/4 tsp baking powder (lightens the crumb a touch)
• ### CINNAMON RIPPLE
• 75 g light brown sugar, packed (1/3 cup)
• 2 tsp ground cinnamon
• 10 g all-purpose flour (1 Tbsp)
• Pinch fine salt
• (Optional) 1 tsp espresso powder or 1 tsp natural cocoa (for colour and depth)
• ### BATTER
• 300 g all-purpose flour (2 1/2 cups)
• 40 g cornstarch (1/3 cup) → *or substitute with 340 g cake flour total*
• 2 1/2 tsp baking powder
• 1/2 tsp baking soda
• 3/4 tsp fine salt
• 115 g unsalted butter, room temperature (1/2 cup)
• 80 g neutral oil (1/3 cup; e.g., sunflower)
• 200 g granulated sugar (1 cup)
• 80 g light brown sugar, packed (1/3 cup)
• 3 large eggs, room temperature
• 240 g full-fat sour cream, room temperature (1 cup)
• 120 g buttermilk, room temperature (1/2 cup)
• 1 Tbsp (15 ml) pure vanilla extract
• (Optional) 1/4 tsp almond extract (lovely with the nutty streusel)
• ### GLAZE
• 120 g powdered sugar (1 cup)
• 1–2 Tbsp (15–30 ml) strong espresso or coffee + 1–2 tsp (5–10 ml) milk or cream, to thin
• Pinch salt
• 1/2 tsp vanilla extract
• ### FRUIT (Choose one)
• Apples: 2 medium (300–350 g), peeled and sliced; toss with 1 Tbsp (15 ml) sugar, 1 tsp (5 ml) lemon juice, pinch salt, and 1/2 tsp cinnamon. Sauté in 1 Tbsp (15 ml) butter for 3–4 minutes until just tender; cool and pat very dry.
• Peaches: 2 medium (≈350 g), sliced; toss with 1 Tbsp (15 ml) sugar, pinch salt, and 1/8 tsp ground cardamom. Roast on parchment at 400°F (205°C) for 8–10 minutes to drive off moisture; cool and pat dry.

Instructions

1. 1

   Preheat the oven to 350°F (175°C) with the rack in the lower-middle position; grease and line a 9×13 inch (23×33 cm) metal pan with a parchment sling.

2. 2

   Brown the butter: cook it over medium heat until the milk solids are nutty and amber coloured; scrape everything into a bowl. Cool until opaque and just barely warm. In a separate bowl, whisk together the flour, sugars, cinnamon, and salt (and baking powder if using). Drizzle in the browned butter and toss with a fork until clumps form. Fold in the nuts if using. Refrigerate while you make the batter (cold crumbs make a better craggy top).

3. 3

   Whisk together the flour, cornstarch, baking powder, baking soda, and salt.

4. 4

   In a stand mixer with the paddle attachment (or with a hand mixer), beat the soft butter and both sugars on medium-high speed until light and slightly fluffy, about 2–3 minutes.

5. 5

   Stream in the oil on medium speed to emulsify (this creates a silky batter and finer crumb).

6. 6

   Beat in the eggs one at a time, scraping down the bowl. Mix in the vanilla (and almond extract if using).

7. 7

   Whisk together the sour cream and buttermilk.

8. 8

   On low speed, add the dry ingredients in 3 additions, alternating with the sour-cream mixture in 2 additions, beginning and ending with the dry ingredients. Mix just until no flour pockets remain. The batter will be thick but spreadable.

9. 9

   Spread half the batter into the greased and parchment-lined 9×13 inch (23×33 cm) pan (an offset spatula helps). Evenly sprinkle all of the Cinnamon Ripple over it. If using fruit, arrange it in a thin single layer over the ripple (avoid overlaps). Scatter about ⅓ of the cold streusel over the fruit or ripple. Dollop and gently spread the remaining batter over the top (it's okay if a little ripple peeks through). Finish with the remaining streusel—big clumps on top are the goal.

10. 10

    Bake at 350°F (175°C) for 42–60 minutes (start checking at 40 minutes). The cake is done when a toothpick inserted in the centre has a few moist crumbs (not wet), and/or the internal temperature reads 205–208°F (96–98°C).

11. 11

    Cool the cake for 20 minutes in the pan, then use the sling to lift it onto a rack. Cool until just warm for neat slices.

12. 12

    Whisk together the glaze ingredients to a thick drizzle consistency and flick over the cooled-to-warm cake. (Optional but delightful.)

13. 13

    Toss the apples with the sugar, lemon, salt, and cinnamon. Sauté them in butter for 3–4 minutes until just tender; cool and pat very dry.

14. 14

    Toss the peaches with the sugar, salt, and cardamom. Roast them on parchment at 400°F (200°C) for 8–10 minutes to drive off moisture; cool and pat dry.