Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13 inch pan. Sift together the flour, cinnamon, baking soda and salt. Set aside. In a large bowl, cream the butter, sugar and vanilla until light and fluffy. Beat in the eggs one at a time, then stir in the melted chocolate. Alternately beat in the flour mixture and the milk, mixing just until incorporated. Stir in jalapeños. Pour into a 9x13 inch pan. Bake in the preheated oven for 30 to 35 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow to cool.