Toast the sesame seeds in a large skillet over medium-low heat, stirring constantly, until golden, 7 to 10 minutes. Transfer to a bowl and let cool completely.
Beat the butter and brown sugar in a large bowl with a mixer on medium-high speed until light and fluffy, 3 to 5 minutes. Add the egg, vanilla, salt and baking powder and beat until combined, scraping down the bowl as needed. Reduce the mixer speed to low; add the flour and 1/4 cup of the toasted sesame seeds and beat until just combined. Cover with plastic wrap and refrigerate until firm, about 30 minutes to an hour.
Position racks in the upper and lower thirds of the oven and preheat to 350 degrees F. Line 2 baking sheets with parchment paper or aluminum foil and butter the parchment or foil. Form teaspoonfuls of dough into small balls, then roll in the remaining 1/2 cup toasted sesame seeds, pressing to coat. Arrange the balls about 2 inches apart on the prepared baking sheets.
Gently flatten each ball with the palm of your hand.
Bake, switching the position of the pans halfway through, until dark golden around the edges, 15 to 20 minutes. Let cool 1 minute on the baking sheets, then carefully remove the cookies with a thin metal spatula and transfer to racks to cool completely.
For the Cheese:
Combine the mascarpone cheese, cheddar cheese, parmesan cheese, dried cranberries, and salt in a medium mixing bowl. MIx well.
Spread a thick layer on each cracker or serve along side crackers as a spread.