Preparation

1. Preheat oven to 350°F. Grease, spray or line baking sheets with parchment paper.
2. In a small bowl, whisk together oil, cocoa, vanilla and espresso powder until smooth. Set aside.
3. In a another bowl, cream butter and sugar until pale yellow and fluffy. Add eggs, one at a time, beating well after each addition.
4. Add cocoa mixture to butter mixture, stirring until completely combined.
5. Sift together flour, soda and salt and add to the chocolate mixture, mixing until combined. (Dough will be quite stiff.)
6. Using a soup spoon, scoop balls and place 1 inch apart on prepared baking sheets. Bake 12 to 15 minutes until tops bounce back when lightly pressed.
7. Allow to cool for 5 minutes on baking sheets, then transfer to cooling racks. While cookies are still warm, use the back of a teaspoon to gently press an indentation in the center of each cookie.
8. Meanwhile, make Chocolate Filling:
9. In a small saucepan, heat cream to boiling, then remove from heat and quickly pour over chopped chocolate. Let stand for 3 minutes then whisk until chocolate has melted and mixture is smooth
10. To finish, scoop a teaspoon of filling into the center of each cookie. Cool and serve. Cookies may be stored, tightly covered, at room temperature for 2-3 days or frozen up to 2 months.