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1
Preheat oven to 350 degrees.
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2
In a mixing bowl, whisk together flour, salt, and baking soda, then whisk in quick oats, set aside.
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3
In the bowl of an electric stand mixer fitted with the paddle attachment, whip together butter, light-brown sugar and granulated sugar on medium-high speed until pale and fluffy, about 3-4 minutes.
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4
Blend in peanut butter.
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5
Stir in eggs one at a time, mixing after each addition until combine.
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6
Mix in vanilla.
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7
With mixer set on low speed, slowly add in dry ingredients and mix until combine.
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8
Spread mixture into an even layer into a 15 by 11-inch rimmed cookie sheet (it will be fairly thin once spread).
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9
Bake in preheated oven 13 - 15 minutes, until lightly golden.
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10
Remove from oven and allow to cool 5 minutes, then dollop remaining 3/4 cup peanut butter by the spoonfuls over peanut butter bars.
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11
Allow dolloped peanut butter to rest about 1 minute then carefully spread peanut butter into an even layer over top.
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12
Prepare chocolate frosting according to direction listed and spread over peanut butter layer.
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13
Allow to cool (if you can handle waiting) before cutting into squares.
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14
Store in a single layer in an airtight container at room temperature.
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15
For the chocolate frosting:
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16
Melt butter in a medium saucepan over medium heat.
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17
Whisk in cocoa powder, then whisk in milk and bring mixture just to a boil.
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18
Once mixture reaches a boil, remove from heat and stir in vanilla extract.
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19
Add in powdered sugar and mix until well blended.
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20
Immediately pour frosting over peanut butter layer and spread into an even layer (frosting sets quickly so I wouldn't recommend being to meticulous with the design like I tried to be, because then you'll end up with a slightly grainy looking frosting like I did).
