Place half the flour into the butter mixture and mix through until just combined. Then add in the other half and mix until a soft pliable dough forms. Knead the dough a few times in the bowl until the dough comes together.
Press ⅔ of the dough into the bottom of the lined cake tin until it is evenly and smoothly pressed into the tin. Evenly spread the jam over the layer of biscuit dough. Then crumble the last ⅓ of the biscuit dough over the top of the jam.
⅓ - ⅔ cup jam
Bake the jam slice for 35 to 45 minutes or until the biscuit dough is beautifully golden brown. Remove from the oven and allow the squares to cool completely in the tin. When the jam squares are cool, remove them from the tin and slice them into 16 to 25 squares or bars.
All temperatures stated are for conventional ovens. Decrease the temperature by 20°C/25°F or gas mark 1 for "fan" or air-fryers.
Video
Notes
If the butter is not soft enough to whisk, simply pop it into the microwave and soften in 10 seconds bursts, do not allow it to melt completely.
Any fruit jam can be used in these jam squares (or jam bars or jam slices). Popular jams include apricot, strawberry, raspberry or even boysenberry jam, the choice is yours. The amount of jam within the jam slice ranges from ⅓ - ⅔ cup jam (this is dependent on how much jam you want in your jam slice, measure with your heart).
Jam vs jelly - Jam is a preserve that is made from whole or cut-up fruit, while jelly is made from fruit juice alone. For this recipe, I'm fairly certain that jelly will work just fine.
Knead the dough 3 to 5 times to bring the dough together.
This pan is a line in a way that allows the slice to be lifted out of the tin with ease. The baking paper also reaches up both sides of the pan - this is to stop the jam from cooking onto the edges of the pan. My baking paper is wide enough to cover all 4 sides, however, you may need to double-sling the baking paper.
Storage & Freezing
These jam squares can be stored in an airtight container for 3 to 4 days, or up to 2 months when frozen. Baked jam squares can be frozen in an airtight freezer-safe container once completely cooled. If layering the jam bars, separate them using a piece of baking paper. Allow the bars to defrost at room temperature before serving.