Preheat oven to 350°F (175°C).
In a mixing bowl, cream together butter, brown sugar, and granulated sugar until light and fluffy.
Beat in the egg and vanilla extract.
In another bowl, whisk together buckwheat flour, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Fold in the chocolate chips.
Drop spoonfuls of dough onto a baking sheet and bake for 10-12 minutes or until golden brown.
Let cookies cool completely.
In a trifle dish, layer crumbled cookies and whipped cream. Repeat layers until the dish is filled.
Chill in the refrigerator for at least 1 hour before serving.