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1
Preheat oven to 375.
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2
Line baking sheets with parchment paper.
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3
For Cookies: Combine flour, cocoa, baking soda, baking powder, and salt in medium bowl; set aside.
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4
Beat together sugar, butter, vanilla and egg in large bowl with electric mixer on medium speed until well combined.
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5
Stir in milk.
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6
Gradually beat in flour mixture on low speed.
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7
Drop batter by rounded tablespoonfuls 2 inches apart onto prepared baking sheets.
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8
Bake until edges appear set, 7 to 9 minutes.
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9
Cool on pan 1 minute.
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10
Remove to wire rack and cool completely.
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11
For White Chocolate Mint Buttercream Filling: Combine white chocolate and 3 tablespoons cream in microwave-safe bowl.
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12
Heat for one minute at medium (50%) power, stirring at 30-second intervals until melted and smooth.
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13
Cool to room temperature.
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14
Beat butter in large bowl with electric mixture on medium speed until creamy.
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15
Gradually beat in powdered sugar, the remaining 2 tablespoons heavy cream, mint extract, vanilla and salt on low speed until blended.
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16
To assemble, spread the bottom sides of half the cookies with the White Chocolate Mint Buttercream Filling.
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17
Top with the remaining cookies, bottom sides down; press gently together.
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18
Sprinkle the edges of the buttercream with crushed peppermint candies.