1 ½cupsold-fashioned whole-rolled oatsnot quick cook or instant
1cupall-purpose flour
pinchsaltoptional and to taste
1cupsemi-sweet chocolate chipsfor batter
half of one 14-ounce can sweetened condensed milkjust eyeball it
about 1/3 cup semi-sweet chocolate chipsfor sprinkling
Instructions
Preheat oven to 350F. Line an 8-by-8-inch baking pan with aluminum foil, spray with cooking spray; set aside.
In a large, microwave-safe bowl melt the butter, about 1 minute on high power.
Wait momentarily before adding the egg so you don’t scramble it. Add the egg, brown sugar, vanilla, and whisk until smooth.
Add the oats, flour, and stir until just combined, don’t overmix.
Turn three-quarters of the batter out into prepared pan, smoothing it with a spatula to form a crust; reserve remainder and set aside.
In a medium microwave-safe bowl, add 1 cup chocolate chips, pour sweetened condensed milk over the top, and heat on high power until the chips melt and mixture can be stirred smooth, about 45 to 60 seconds.
Evenly pour chocolate mixture over crust, smoothing the top lightly with a spatula. Work somewhat quickly because mixture begins to set up after a couple minutes.
Evenly crumble the reserved oatmeal mixture over the chocolate layer. I find it easiest to make heaping 1-tablespoon-sized ‘blobs’, and after all the blobs are in the pan, smoosh and smooth them together with a spatula. The entire surface will not be covered and there will be some gaps.
Bake for about 25 minutes, or until top is set; it should be very pale in color for soft bars; golden colored means bars will be crunchier.
Evenly sprinkle bars with about 1/3 cup chocolate chips, or as desired. Chips will soften and melt slightly. Avoid jostling the pan because it will cause chips to melt more rather than stay intact.
Set pan aside and allow bars to cool in pan for at least 1 hour before slicing and serving.
Notes
Bars will keep airtight at room temperature for up to 1 week, or in the freezer for up to 6 months.