Instructions

1. 1
   Preheat oven to 190 °C (375 °F).
2. 2
   Mix the flour, salt, and sugar in the bowl of a food processor.
3. 3
   Cut in the cold butter and mix with a series of short pulses, until the mixture resembles pea-meal. The crust will have a flakier texture if you avoid mixing the butter in too much.
4. 4
   Gradually pulse in ice water, 1 tbsp at a time, until the dough just holds together. You may not need all the water.
5. 5
   Divide into two discs, wrap in plastic, and chill for at least 30 minutes.
6. 6
   Roll the dough to ⅛ inch (3 mm) thick. Cut into 4 inch (10 cm) rounds.
7. 7
   Gently press each round into a cup of a non-stick muffin pan. Chill the pan chill while making the filling.
8. 8
   Cream the butter and brown sugar until smooth.
9. 9
   Whisk in the eggs until light and slightly frothy.
10. 10
    Stir in maple syrup, vanilla, vinegar, and salt. Mix until smooth, but not foamy.
11. 11
    Fill tart shells with the filling to about about two-thirds full.
12. 12
    Sprinkle a spoonful of chopped nuts over the top of each tart.
13. 13
    Bake for 15–18 minutes until the centre is gooey and slightly runny, which is the traditional Canadian style. If you prefer a firmer tart, cook for 20 minutes.
14. 14
    Let cool in the tin for 10 minutes, then carefully lift out and cool on a rack.