Step 1
Preheat oven to 425°F (220°C). Prepare two muffin tins by spraying the inside of every other cavity or lining with cupcake liners. Spray the top of the muffin tins with cooking spray (to prevent the muffin tops from sticking) then set aside.
Step 2
In a small bowl, stir together the strawberry preserves and lemon juice until combined. Set aside.
Step 3
In the bowl of a food processor, combine the Domino® Golden Sugar, Dark Brown Sugar, flour, walnuts, cinnamon, and butter. Pulse until the topping begins to clump together and become crumbly. Set aside.
Step 4
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter, Domino® Golden Sugar, and Dark Brown Sugar together on high speed until smooth and creamy, about 3 minutes. Add the eggs, sour cream, and vanilla extract. Beat on high speed until the mixture is combined and uniform in texture. Scrape down the sides and bottom of the bowl as needed.
Step 5
Whisk the baking powder, baking soda, salt, and flour together in a medium bowl. Pour the dry ingredients into the wet ingredients, add the buttermilk and diced strawberries, and mix on low speed until everything is combined.
Step 6
Spoon 4.5 tablespoons of batter into each cup or liner, filling each to the top. Then spoon about a teaspoon of the strawberry preserves/lemon juice mixture into each cup, swirling with a toothpick or skewer. Press a handful of the crumb topping into the top of each muffin.
Step 7
Bake for 5 minutes at 425°F (220°C) degrees, then keeping the muffins in the oven, lower the oven temperature to 350°F (180°C) and bake for 15-17 more minutes or until a toothpick inserted in the center comes out clean.
Step 8
Cool the muffins in the pan on a wire rack for 15 minutes, then use an offset spatula to run underneath the edges of the strawberry muffin tops to prevent them from sticking in the pan. Be careful to just run the offset spatula under the edges—you don't want to accidentally cut into the muffin and remove the muffin’s top! After unsticking the muffin tops, keep cooling the muffins in the tins completely to room temperature.
The muffins are best on the day that they’re made, but can be individually wrapped in plastic or kept in an airtight container and stored at room temperature for up to 3 days.