Heat the oven to 350°F. Line one 8x8-inch baking pan with parchment paper, leaving an overhang on two sides, or grease the pan well.

In a medium bowl, whisk 1 1/2 cups all-purpose flour, 1 teaspoon baking powder, 1 teaspoon baking soda, 1 1/2 to 2 teaspoons homemade chai spice blend, and 1/2 teaspoon salt.

In a large bowl, whisk 2 large eggs, 1/2 cup neutral oil or melted and cooled unsalted butter, 1/2 cup packed light brown sugar, 1/3 cup pure maple syrup, 3/4 cup milk, and 1 tablespoon vanilla extract until smooth.

Add the dry mixture made with 1 1/2 cups flour to the wet mixture made with 2 eggs and 1/2 cup oil or butter. Stir just until no dry flour remains. The batter should be pourable, not thin or watery.

Pour all of the batter into the prepared 8x8-inch pan and smooth the top. Bake at 350°F for 25 to 35 minutes, until the center springs back lightly and a toothpick comes out clean or with a few moist crumbs.

Cool the baked 8x8-inch cake in the pan for at least 1 hour. The cake must feel completely cool before frosting.

Beat 1/2 cup softened unsalted butter and 4 ounces softened cream cheese for 2 to 3 minutes, until smooth and fluffy.

Add 1 1/4 cups powdered sugar, 2 tablespoons pure maple syrup, 2 tablespoons cooled caramel sauce, 1 teaspoon vanilla extract, and 1/2 teaspoon homemade chai spice blend. Beat on low until combined, then beat for 1 minute until silky. Add the remaining 1/4 cup powdered sugar if the frosting needs more body.

Spread all of the caramel maple frosting over the completely cooled 8x8-inch cake. If desired, finish with 1 to 2 tablespoons caramel sauce and 1 pinch chai spice, then cut into 9 squares.