Heat the oven to 350°F. Line a baking pan with parchment or lightly grease it. The pan should be ready before the batter is mixed.
In a large bowl, stir together the oats, flour, baking powder, and salt. The mix should look dry and evenly combined.
Add the sweetener, melted butter or oil, and eggs. Stir until the batter comes together and looks thick but spreadable.
Fold in the chocolate chips. They should be spread through the batter, not clumped in one spot.
Spread the batter into the pan. Press it into an even layer so it bakes evenly.
Bake until the top is lightly golden and the center feels set when pressed. The edges should look firm.
Let the bars cool in the pan before cutting. This helps them hold their shape.