Preheat your oven to 350°F (180°C). Make sure to give it enough time to get hot so that your muffins bake evenly. While the oven heats, prepare your muffin pan by spraying it with baking spray that contains flour or lining the wells with paper liners to avoid sticking.
In a medium bowl, whisk together the all-purpose flour, baking powder, ground cardamom, ¾ teaspoon of kosher salt, and ground ginger. This step ensures that your dry ingredients are well mixed, preventing clumps that could affect your muffins' texture.
In a large mixing bowl, combine the granulated sugar, dark brown sugar, eggs, and lemon zest. Whisk these ingredients together until they’re light and fluffy - this will help to incorporate air into the batter, making your muffins extra light.
Add in the vegetable oil and whole milk, whisking until everything is well combined. You want a smooth mixture that’s completely homogenous.
Now, gradually add the flour mixture to the wet ingredients, folding gently until just combined. Be careful not to overmix; you want to keep the batter fluffy for those perfect muffins.
Let the batter sit for about 30 minutes. This resting period can enhance the muffins' texture, making them more tender.
After the resting period, spoon the batter into the prepared muffin cups, filling them about three-fourths full (roughly 73 grams each). It’s important not to overfill, or they’ll overflow as they bake.
Next, take your Lemon Curd and place it in a pastry bag. Cut a ½-inch opening in the tip and pipe the curd into the center of each muffin well until the batter reaches the top edge. Be careful not to touch the bottom or sides of the well; this ensures the curd stays inside while baking. If any curd spills over, use a kitchen towel to gently tap the pan on the counter to settle it.
Top each muffin with about 2 teaspoons of remaining batter (about 14 grams each) and sprinkle the Oat-Pecan Streusel generously on top, approximately 1½ tablespoons each. This will give your muffins a nice crunch!
Place the muffin pan in the preheated oven and bake until a wooden pick inserted into the center comes out clean, which should take about 30 minutes. The muffins will rise beautifully and turn a lovely golden color. Once done, let them cool in the pan for about 10 minutes before transferring them to a wire rack to cool completely. Drizzle with Lemon Glaze just before serving. They’re best enjoyed warm or at room temperature!