Preheat oven to 350°F (177°C). Grease and line a 9-inch baking pan with parchment paper, ensuring that 2 of the opposite facing sides have a 2-inch overhang to make unmoulding easier.
In a bowl, whisk together 1 cup (125 grams) of the all-purpose flour, bread flour, salt, and baking powder until thoroughly combined.
Place butter in a large microwaveable bowl, and heat until just melted. With a whisk, whisk in the Redpath® Golden Yellow Sugar until combined. Let cool slightly.
In another bowl, lightly whisk together the eggs, yolk, vanilla extract, and lemon zest. Pour egg mixture into the warm (not hot) sugar-butter mixture. Stir with the whisk until completely combined.
With a rubber spatula, mix in the dry ingredients. Mix until just combined.
Transfer half of the batter into the prepared pan. Evenly smooth the batter out with the spatula or a small offset spatula.
Sift the remaining 1 tablespoon (8 grams) of flour over the cooled caramelized apples. Stir to incorporate. Spread the apple mixture evenly over the batter in the pan. Add the remaining batter over the apple mixture and smooth the top.
Place pan into the preheated oven and bake for 30 to 35 minutes, or until top is pale golden in colour, middle is just set, and a skewer inserted into the centre of the pan comes out with a few moist crumbs attached.
Remove from oven and place pan onto a wire cooling rack to cool completely. When blondies are completely cooled, lift the parchment paper overhang to aid in the removal of the bars.
With a sharp chef’s knife or serrated bread knife, slice blondies into bars.
Blondies can be kept in an airtight container at room temperature for about a week or wrapped well and frozen for up to 3 months.