1. Cream the butter, oil, sugar, vanilla and salt in the bowl of a stand mixer fitted with a paddle attachment, just until the mixture is smooth. Do not over beat, as this will incorporate air into the dough, which may lead to spreading.
2. Add the egg and mix just until incorporated.
3. Add the cornstarch, cocoa powder and flour. If you will be rolling/cutting the cookies right away, you may need a little more flour. The dough becomes drier as it sits, so if you are planning to chill and roll/cut later, be sure to use less flour.
4. Preheat the oven to 375 degrees F.
5. Roll the dough to a thickness of 1/4 inch, between two sheets of parchment paper. Rolling pin rings will help you to achieve an even thickness.
6. Bake on parchment-lined baking sheets for 9 to 12 minutes, depending upon the size of the cookie. The cookie should look dry on the surface, and be firm around the edges and soft in the middle.
7. Cool completely before decorating.

 Directions:

1. Mix together (with a spoon) flour, tea and salt in a separate bowl and set aside.

2. Mix butter and sugar with an electric mixer until pale and fluffy. In a food processer, grind the dried lavender and tea leaves until it resembles fine crumbs. Slowly mix in flour and lavender earl grey mixture until just combined.

3. Divide the dough into half and transfer each half to a piece of baking paper. Shape them into flat discs and freeze for an hour. 

4. Preheat oven to 175°C. Cut the dough into your desired shape. I used cat cookie cutters.

5. Bake for about 13 to 15 minutes until edges turn golden. Let them cool and your Earl Grey Lavender cookies are ready!