Preheat your oven to 350 degrees Fahrenheit.
In a medium-sized bowl, whisk together the flour, baking powder, baking soda, salt, and chai spice mix.
In a separate bowl, cream together the butter and sugar until light and fluffy. Add in the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
Gradually add in the dry ingredients, alternating with the milk, until the batter is smooth and well combined.
Fold in the lemon juice and lemon zest, being careful not to overmix.
Pour the batter into a greased 9-inch cake pan and bake for 35-40 minutes, or until a toothpick inserted into the center of the cake comes out clean.
Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.
Serve the cake with a dusting of powdered sugar or your favorite frosting.