Preheat the oven to 350°F (180°C, or gas mark 4).

Lightly coat an 8-inch (20-cm) square baking pan with nonstick spray.

Combine the vinegar and soymilk in a medium mixing bowl.

Let it sit for a few minutes to curdle into a buttermilk-like texture.

In a large mixing bowl, whisk together the whole wheat pastry flour, ground oats, cinnamon, ginger, baking powder, baking soda, and fine sea salt.

Whisk the molasses and canola oil into the curdled buttermilk mixture.

Gently fold the wet ingredients into the dry ingredients, being careful not to overmix.

Fold in the raisins and nuts, if using.

Pour the batter into the prepared pan and spread evenly.

Bake for 25 minutes, or until a toothpick inserted into the center comes out clean.

Place the pan on a wire rack to cool for 15 minutes.

Then transfer the cake to the rack to cool completely before slicing or storing.