1. Preheat oven to 350°F (175°C) and position rack in center.

2. Grease and line a 9×13-inch pan or two 8-inch round pans with parchment and spray.

3. In a bowl whisk flour, baking powder, baking soda, salt, cinnamon, ginger, cardamom, and nutmeg.

4. In another bowl whisk brown sugar, granulated sugar, oil, eggs, pumpkin purée, chai tea, and vanilla until smooth.

5. Add dry ingredients to wet in two additions, stirring until just combined.

6. Pour batter into prepared pan(s) and smooth top with a spatula.

7. Bake 30–35 minutes (sheet) or 25–30 minutes (rounds) until a toothpick comes out clean.

8. Let cake cool in pan 10 minutes, then transfer to a rack to cool completely before frosting.