Grandma Ruth whipped up this 4 ingredient masterpiece every Sunday after church.

For a slightly lighter flavor, you can use 2% milk instead of whole milk, though the filling will be a bit less rich and may be slightly looser; chill thoroughly before slicing. If you prefer a stronger peanut flavor, increase the peanut butter to 1 1/4 cups and add powdered sugar a tablespoon at a time until you reach a crumbly consistency that still blends smoothly with the milk.

Crunchy peanut butter can be used for added texture, but be sure to break up the crumb layer well so it spreads evenly in the crust. A pinch of salt (from your pantry, not counted in the four core ingredients) intensifies the peanut flavor without making the pie taste salty.

For a chocolate twist that still respects the four-ingredient spirit, serve each slice with a drizzle of chocolate syrup rather than adding any new ingredients to the filling itself.

Food safety tips: Always bake the pie crust fully; an underbaked crust can stay doughy and unpleasant under a creamy filling. Let the crust cool completely before adding the milk-based filling to avoid condensation and a soggy bottom.

Use fresh milk that has been kept refrigerated at 40°F (4°C) or below, and return the pie to the refrigerator promptly after serving—do not leave it at room temperature for more than 2 hours. Store leftovers covered in the refrigerator and eat within 3 days for best quality and safety.