01 -
In a small bowl, whisk together the flour and cornstarch. Set aside.
02 -
In a medium bowl, add butter and sugar. Beat until light and fluffy, about 3 minutes. Add egg, vanilla, and salt. Sift in the cocoa powder and mix until well combined.
03 -
Add the dry ingredients to the wet ingredients and mix until just combined. Cover and chill the dough for 30 minutes in the freezer or 1 hour in the refrigerator.
04 -
Preheat the oven to 350°F (175°C). Scoop the dough by tablespoonfuls, roll into balls, and place onto parchment-lined baking sheets 1 inch apart. Gently flatten each ball and press a deep indentation in the center of each using the handle of a wooden spoon.
05 -
Bake the cookies on the center rack until edges are set, 10-12 minutes. Once baked, use the back of a wooden spoon to press the indentation down again. Let the cookies cool on wire racks.
06 -
Place the chopped pecans on a baking sheet and bake until golden brown and fragrant, about 10 minutes, stirring halfway through.
07 -
In a heavy-bottomed saucepan over medium-high heat, add sugar and stir with a whisk until fully melted and golden amber in color. Add butter and whisk well. Remove from heat and whisk in heavy cream, salt, cinnamon, and nutmeg until incorporated. Mix in the toasted pecans.
08 -
Spoon the prepared caramel filling into the indentation of each thumbprint cookie.
09 -
Melt the chocolate chips and coconut oil in the microwave in 30-second increments until smooth. Pipe or drizzle the chocolate over the cookies. Optionally, sprinkle flaky sea salt over the top.