Start by melting the butter in a saucepan over medium heat. Stir continuously until the butter turns golden brown and develops a nutty aroma. This step is key because browned butter adds deep flavor to the cookie base.

Allow the butter to cool slightly before mixing it with other ingredients. This prevents the eggs from cooking when added.

In a large mixing bowl, combine the browned butter, brown sugar, and granulated sugar. Whisk until the mixture looks smooth and slightly creamy.

Add the eggs, heavy cream, and vanilla extract. Continue mixing until the ingredients are fully incorporated and the mixture becomes glossy.

In a separate bowl, whisk together flour, salt, baking powder, baking soda, and cinnamon. Mixing the dry ingredients separately ensures they distribute evenly in the dough.

Gradually add the dry mixture to the wet ingredients while stirring gently. Mix only until the dough forms.

Gently fold the fresh blueberries into the dough using a spatula. Try not to crush them so they keep their shape during baking.

Fresh blueberries give the best texture, but frozen ones can also work if used straight from the freezer.

Transfer the cookie dough into a greased 10-inch skillet. Spread it evenly using a spatula so it bakes uniformly.

Drop spoonfuls of blueberry preserves across the top and gently swirl them into the dough with a knife.

Place the skillet in the preheated oven and bake until the edges turn golden brown. The center should remain slightly soft and gooey.

Remove from the oven and let it cool for a few minutes before serving. The skillet will continue cooking the center slightly from residual heat.