Use a food processor or blender to blend the coconut oil, almond butter, collagen, vanilla bean powder and stevia together.Line a 8.5 x 4.5 (standard) bread pan with parchment paper.Pour almond butter mixture into the bread pan. Use a spatula to spread the mixture evenly across the bottom of the pan.Place the pan in the freezer.In a small saucepan, warm the coconut oil for 2-4 minutes over low heat or until it's melted.Mix cocoa powder, coconut oil and liquid stevia together.Remove the almond butter from the freezer and pour the chocolate glaze over the top.Carefully spread the chocolate over the top without mixing the two layers together.Return the almond butter bars to the freezer.Freezer for approximately 1 hour or until the bars are frozen.Cut bars into squares and serve. Store leftover bars in the freezer.