Lemon Blueberry Muffins

Instructions

Blueberry Jam

1. In a small bowl, stir the cornstarch and cold water together until a smooth slurry. Set aside.

2. In a small saucepan, combine the blueberries, sugar, lemon juice, and lemon zest (if using).
3. Cook over medium heat, stirring occasionally, until the berries begin to release juices and soften, about 3–4 minutes.
4. Gently mash some of the berries with a fork or spatula, leaving a few whole for texture.
5. Stir the cornstarch slurry into the berries and cook, gently stirring frequently with a spatula, until thickened, glossy, and reaches a temp of 210–215°F, about 2–3 more minutes. Do not exceed this temperature.
6. Remove from heat and let cool to room temperature (about 15–20 minutes). It will thicken more as it cools.

Crumb Topping

1. In a medium bowl, whisk together the flour, granulated sugar, brown sugar, and salt.

2. In a small bowl, mix the melted butter and vanilla.
3. Add the butter mixture to the dry ingredients and stir with a fork until crumbly and resembling wet sand.
4. Cover and refrigerate until ready to use.

Muffin Batter

1. Preheat the oven to 425°F and position a rack in the center. Line a 12-cup muffin tin with paper liners (12 tulip liners or about 14 regular liners). If using regular liners, lightly grease the top of the pan in case of any overflow.

2. In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
3. In a large bowl, combine the sugar and lemon zest. Massage with your fingers for about 30 seconds to release the oils.
4. Add the melted butter and oil to the lemon sugar and whisk until lighter in color, about 1 minute.
5. Whisk in the eggs, lemon juice, sour cream, milk, and vanilla until smooth, about 30–45 seconds.
6. Gently fold in the dry ingredients in two additions with a spatula until just combined and no flour streaks remain.
7. Toss the blueberries with 1 tsp of flour to prevent sinking, then gently fold them into the batter. Do not overmix.

Assembly

1. Fill the liners with batter until just below the top (about 6-Tbsp for tulip and 4-Tbsp scoop for regular).

2. Spoon 1-2 tsp of the cooled jam over each muffin and gently spread with a fork or knife, try not to push it deep into the batter.
3. Break up the chilled crumb topping with a fork and sprinkle evenly on top.
4. Bake at 425°F for 8 minutes to create a dome.
5. Without opening the oven door, reduce the temperature to 350°F and continue baking for 9–14 minutes, depending on liner size. Muffins are done when a toothpick inserted in the center comes out with a few moist crumbs and the crumb is lightly golden. If crumble browns too quickly, tent loosely with foil.
6. Cool muffins in the pan for 5 minutes, then transfer to a wire rack to cool slightly before glazing or serving.

Lemon Glaze (optional)

1. Stir together all glaze ingredients in a small bowl. For a thicker glaze, add more sugar; for a thinner one, add more lemon juice 1 tsp at a time.

2. Drizzle over cooled muffins and serve at room temperature or slightly warmed.