Via Dorie Greenspan: From my Home to Yours - adapted by Isabelle
For the oatmeal layer:
240 g (2 cups) all-purpose flour
5 ml (1 teaspoon) baking soda
5 ml (1 teaspoon) salt
200 g (1 cup) unsalted butter, at room temperature
360 g (2 cups) brown sugar
2 large eggs
10 ml (2 teaspoons) pure vanilla extract
240 g (3 cups) old-fashioned (rolled) oats
100 g (1 cup) pecans, coarsely chopped
For the butterscoth layer:
300 ml (14-ounce) can sweetened condensed milk
300 g (2 cups) butterscoth chips
30 ml (2 tablespoons) unsalted butter
1 ml (¼ teaspoon) salt
5 ml (1 teaspoon) pure vanilla extract
Preheat oven to 350°F (180°C). Butter a 9-by-13-inch baking pan, and place the pan on a baking sheet.
To make the oatmeal layer:
Whisk together the flour, baking soda and salt. Working with a stand mixer, preferably fitted with a paddle attachment, or with a hand mixer in a large bowl, beat the butter on medium speed until it is soft and creamy. Add the brown sugar and beat for 2 minutes, then add the eggs, one at a time, beating for a minute after each egg goes in. Beat in the vanilla. The mixture should be light and fluffy. Reduce the mixer speed to low and add the dry ingredients, mixing just until they disappear. Still on low speed, or working by hand with a rubber spatula, stir in the oats and chopped pecans. Set aside 1½ to 2 cups of the mixture, then turn the remaining dough into the buttered pan. Gently and evenly press the dough over the bottom of the pan. Set aside while you prepare the next layer.
To make the butterscotch layer:
Set a heat-proof bowl over a saucepan of simmering water. Put the condensed milk, butterscotch chips, butter, and salt in the bowl and stir occasionally until the milk is warm and the chocolate and butter are melted. Remove the bowl from the pan of water and stir in the vanilla. Pour the warm butterscothch over the oatmeal crust, then scatter the remaining oatmeal mixture over the top.. Bake for 25 to 30 minutes, or until the topping is golden brown. Transfer the baking pan to a rack and cool for about 2 hours. Refrigerate for at least 1 hour before cutting. Cut into 50 bars, each roughly 2 cm par 2 cm (1 by 1 inches).
Bon Appétit!