Step 1

1 Melt the chilled half of the butter in a medium skillet over medium heat, swirling it in the pan occasionally

Step 2

2 It’ll foam and froth as it cooks, and start to crackle and pop

Step 3

3 Once the crackling stops, keep a close eye on the melted butter, continuing to swirl the pan often

Step 4

4 The butter will start to smell nutty, and brown bits will form in the bottom

Step 5

5 Once the bits are amber brown (2 1/2 to 3 minutes or so after the sizzling stops), remove the butter from the heat and immediately pour it into a small bowl, bits and all

Step 6

6 This will stop the butter from cooking and burning

Step 7

7 Let cool for 20 minutes

Step 8

8 Position racks in the upper and lower thirds of the oven; preheat to 350 degrees

Step 9

9 Line several baking sheets with parchment paper

Step 10

10 Combine the remaining 8 tablespoons of room-temperature butter and the brown sugar in the bowl of a stand mixer or use a handheld electric mixer; beat on medium speed for 3 to 5 minutes, until the mixture is very smooth (but not quite fluffy)

Step 11

11 Reduce the speed to medium-low; beat in the vanilla extract and molasses until well incorporated

Step 12

12 Pour the cooled brown butter into the bowl, along with the granulated sugar

Step 13

13 Beat for 2 minutes (medium-low), until smooth; the mixture will lighten in color and become fluffy

Step 14

14 Reduce the speed to low; add the egg and egg yolk, beating for 1 minute, then stop to scrape down the bowl

Step 15

15 Add the flour, kosher salt and baking soda; beat on low speed just until everything is incorporated

Step 16

16 Use a spatula to fold in the chocolate chips and pecans and finish incorporating all of the dry flour bits into the dough

Step 17

17 Scoop the dough in 2-tablespoon-size balls onto the prepared baking sheets, leaving about 2 inches between the balls

Step 18

18 Use a light, two-fingered pinch to sprinkle each portion of dough with coarse or flaky sea salt

Step 19

19 Bake (upper and lower racks) for 12 to 15 minutes until golden brown, rotating the baking sheets top to bottom and front to back halfway through

Step 20

20 Let the cookies rest on the baking sheets for 5 minutes before transferring to a wire rack to cool

Step 21

21 Repeat to use all the dough