Make crusts: Mix flour, cocoa, sugar, and salt in a medium bowl. In second bowl, mix butter, oil, egg, and vanilla. Mix wet mixture into dry. Chill 15 minutes.

Grease mini-muffin cups with cooking spray or oil. Form dough into walnut-size balls; place one in each cup. Gently push dough along bottom and sides of each cup. Chill 15 minutes.

Preheat oven to 375°. Bake crusts 12–15 minutes. Cool completely before removing.

Make filling: Cream together peanut butter and cream cheese. Mix in sugar and vanilla. Whip cream to soft peaks; fold one-fourth into peanut-butter mixture. Gradually fold in remaining whipped cream.

Make glaze: Melt chocolate gently in microwave, 15–30 seconds at a time, stirring after each interval. Mix in oil.

Spoon about 1 teaspoon peanut-butter filling into each crust; smooth tops. Spoon glaze onto tops. Sprinkle with peanuts, if using. Serve, or refrigerate for a firmer texture; remove 5–10 minutes before serving.