10 oz. marshmallow fluff ((aka marshmallow creme, about one and half 7 oz. jars))
Instructions:
Set oven racks in upper and lower third of the oven and preheat oven to 375 degrees. Line 18 by 13-inch baking sheets with parchment paper, set aside.
In a medium mixing bowl whisk together flour, cocoa powder, baking soda and salt. Set aside.
In a large mixing bowl using an electric hand mixer or in the bowl of a stand mixer fitted with the paddle attachment mix together brown sugar, buttermilk, vegetable oil, egg and vanilla extract until well blended.
Add flour mixture and mix just until combined, then pour in hot water and mix just until combined.
Scoop batter out using a medium cookie scoop or 1 1/2 Tbsp at a time, and drop onto prepared baking sheets, spacing 2-inches apart.
Bake first two sheets at a once, rotating sheets halfway through baking, until cookies spring back when touched or toothpick inserted into center comes out clean, about 8 - 10 minutes total.
Let cool about 5 minutes then use a spatula to transfer to a wire rack to cool completely. Bake remaining last sheet of cookies in center of the oven, about 8 - 10 minutes.
In the bowl of an electric stand mixer fitted with the paddle attachment (or using a hand mixer) cream together salted butter, unsalted butter and powdered sugar on low speed until well combined.
Increase mixer speed to high and whip until until light and fluffy, about 4 minutes. Blend in vanilla.
Remove bowl from stand mixer, add marshmallow fluff and fold together using a rubber spatula just until combined.
Chill mixture about 20 minutes to thicken up then fold again. Transfer to a piping bag fitted with a large round tip and pipe over half of the cookies, sandwich a second cookie over the top.
Store cookies in an airtight container set on parchment paper, in a single layer in the refrigerator up to 3 days. Let rest at room temperature about 30 minutes before serving.
Set oven racks in upper and lower third of the oven and preheat oven to 375 degrees. Line 18 by 13-inch baking sheets with parchment paper, set aside.
In a medium mixing bowl whisk together flour, cocoa powder, baking soda and salt. Set aside.
In a large mixing bowl using an electric hand mixer or in the bowl of a stand mixer fitted with the paddle attachment mix together brown sugar, buttermilk, vegetable oil, egg and vanilla extract until well blended.
Add flour mixture and mix just until combined, then pour in hot water and mix just until combined.
Scoop batter out using a medium cookie scoop or 1 1/2 Tbsp at a time, and drop onto prepared baking sheets, spacing 2-inches apart.
Bake first two sheets at a once, rotating sheets halfway through baking, until cookies spring back when touched or toothpick inserted into center comes out clean, about 8 - 10 minutes total.
Let cool about 5 minutes then use a spatula to transfer to a wire rack to cool completely. Bake remaining last sheet of cookies in center of the oven, about 8 - 10 minutes.
In the bowl of an electric stand mixer fitted with the paddle attachment (or using a hand mixer) cream together salted butter, unsalted butter and powdered sugar on low speed until well combined.
Increase mixer speed to high and whip until until light and fluffy, about 4 minutes. Blend in vanilla.
Remove bowl from stand mixer, add marshmallow fluff and fold together using a rubber spatula just until combined.
Chill mixture about 20 minutes to thicken up then fold again. Transfer to a piping bag fitted with a large round tip and pipe over half of the cookies, sandwich a second cookie over the top.
Store cookies in an airtight container set on parchment paper, in a single layer in the refrigerator up to 3 days. Let rest at room temperature about 30 minutes before serving.