Combine the whole wheat flour, all-purpose flour, baking powder, baking soda, salt, cinnamon, and nutmeg in a bowl. Set this dry mixture aside.

In a stand mixer or large bowl, beat the butter, brown sugar, honey, and vanilla until the mixture is pale and creamy. Scrape down the sides of the bowl as needed.

Gradually add the flour mixture to the wet ingredients in four separate additions. Alternate these additions with the heavy cream, scraping the bowl between each addition.

Divide the dough into two equal portions and shape each into a rectangular disk. Wrap each disk tightly in plastic wrap and refrigerate for at least 2 hours, or up to several days.

Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.

On a lightly floured surface, roll out one disk of dough at a time to about 1/8-inch thickness. Cut the dough into 3-inch squares using a knife or pastry wheel.

Arrange the dough squares on the prepared baking sheet, leaving about 1/4 inch space between them. Sprinkle with coarse sugar, if desired.

Bake for approximately 12 minutes, or until the edges of the crackers begin to turn golden brown.

Let the crackers cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.