Easiest Ever Raspberry Jam Bars

Bahan-bahan (16 porsi)

• 125 g / 1 stick unsalted butter (, melted)
• 1/2 cup brown sugar (, tightly packed)
• 1 large egg ((55-60g / 2 oz))
• 1 1/2 cups flour ((plain / all-purpose))
• 1 1/2 cups rolled oats ((traditional oats, not quick, instant or steel-cut))
• 1/2 tsp baking powder
• Pinch salt
• 1 cup raspberry jam ((or other flavour))