In a large mixing bowl, mix together eggs, brown sugar, and vanilla. Add chocolate spread and mix well. Add flour, salt and baking powder and mix. Cover bowl with plastic wrap and refrigerate for one hour.

Preheat oven to 325 degrees Fahrenheit and line four cookie sheets with Gefen Parchment Paper. Drop tablespoonfuls of cookie dough on the cookie sheets so there are eight cookies per sheet (the cookies spread a lot while baking). Dip the tablespoon in a cup of water as you go so the dough slides right out. Bake in preheated oven for 10 minutes.

Remove cookies from oven and gently press a marshmallow half into the center of the cookie. Return cookies to oven and bake for two minutes longer.

Let cookies cool for about 10 minutes. In a double-boiler or microwave, melt white chocolate and drizzle over cookies.