1. Preheat oven to 350 degrees Fahrenheit.
2. Melt the chocolate together with the butter, in a microwave, bain-marie, or double boiler, stirring into a smooth, uniform mixture. Set aside.
3. In the bowl of a mixer, beat the eggs with the sugar for seven minutes.
4. Add the melted chocolate mixture and stir gently with a spatula until combined.
5. Swirl in the ground pecans and cornstarch. Pour into two greased baking pans and bake for 25 to 30 minutes, until an inserted toothpick comes out with a few crumbs stuck to it. It’s important not to over-bake the cake so that it remains moist. Let the cake cool for 10 minutes at room temperature.