Measure out your milk - 2 cups & 1 cup.
Set aside your 2 cups of milk.
Mix flour & cornstarch to the 1 cup of milk - whisk to combine well. Set aside.
Crack your eggs into a separate bowl- whisk & set aside.
In heavy saucepan, melt butter.
Add brown sugar & cook on med until it caramelizes.
While you are whisking this butter/brown sugar mixture- gradually pour in your 2 cups of milk.
Continue to whisk & cook until it bubbles & thickens.
Stir in your remaining milk/flour/cornstarch mixture & whisk well until thickened.
Ladle out 1 cup of your pudding mixture & slowly whisk into your beaten eggs to temper. Whisk until fully blended.
Slowly pour egg mixture into pudding & whisk until well blended.
Cook for 2-3 minutes on med.
Remove from heat & whisk in vanilla extract & pumpkin pie spice.
Pour into individual serving bowls & cover with plastic wrap- laying the wrap directly on the pudding to keep a film from forming.
Refrigerate to firm up at least several hours before serving.
Sprinkle with additional sea salt for serving.