Techniques
Turn a 9x 9 inch square pan greasily.
In big saucepan set over medium heat, melt butter. Combine vanilla and brown sugar. Stir into the oats. Cook over low heat two to three minutes, or until thoroughly mixed. Half of the mixture should be pressed into the bottom of the ready pan. Set aside half for top garnish.
Melt chocolate chips and peanut butter in a small heavy saucepan set over medium heat, stirring often until smooth. Drizzle the chocolate mixture over the pan’s crust, then equally with a knife or the back of a spoon.
Pressing in carefully, crumble the remaining oat mixture over the chocolate layer. Cover; chill 2 to 3 hours or overnight. Before cutting into bars, bring to room temperature.