Sift flour, baking soda, baking powder and salt together in a medium bowl. Set aside.
In a large bowl, cream the butter and both sugars together just mixed.
Add eggs one at a time, mixing well between each addition. Add vanilla and mix until combined.
Gradually add the dry ingredients, paying attention to the dough consistency. The dough should be slightly sticky when touched.
Drop rounded tablespoons onto parchment-lined cookie sheets (or you can grease them), I usually fit a dozen per sheet.
Bake in preheated oven for 8-10 minutes, rotating the sheets halfway and checking at 8 minutes. The cookies should appear done on the edges but still soft in the middle when they are finished cooking.
Let cool on the cookie trays for 5 minutes before transferring to a cooling rack.
Melt chocolate in the microwave in 30-second intervals until totally melted.
Crush peppermints until they are small pieces.
Once cookies are totally cooled, dip cookies halfway in the melted chocolate. Set on a parchment baking tray.