Oatmeal Lace Cookies:

Preheat oven to 360° F / 180° C.  Line a tray with parchment, and set aside until ready to use.

In a medium saucepan, melt the butter over medium-low heat. Add the brown sugar and stir until the sugar has fully dissolved into the butter.

Remove pan from heat. Stir in flour, cinnamon, and salt, followed by vanilla extract. Set aside and allow mixture to cool for a few minutes at room temperature.

Gently stir the egg into the sugar mixture. Add the old-fashioned oats and the chopped ginger, and use a spatula to stir until well-combined.

Drop batter by the spoonful onto prepared tray, allowing 2-3 inches / 5-7 centimeteres of space in between each one (these cookies will spread!)

Using damp fingers or the back of a metal spoon dipped in water, smooth the drops of batter into thin discs. Each unbaked cookie should be about 2.5 inches / 6 centimeters or so in diameter.

Bake in preheated oven for 10-12 minutes, or until nicely golden brown. Remove from oven and allow cookies to cool completely on the tray. While cookies are cooling, prepare the ganache.

Chai-Spiced Chocolate Ganache:

In a small saucepan, warm the cream over low heat. Remove from heat, add the tea bags, and set aside to infuse, at least 15 minutes.

Using a fine mesh strainer, strain the infused cream to remove the tea bags and any loose bits of tea. Reweigh/remeasure the cream, and if necessary, add more cream to make up 160 milliliters.

Return cream to the saucepan and gently rewarm over low heat.

Meanwhile, melt chocolate over a bain marie or double boiler.

Whisk warm chai-infused cream into the melted chocolate, followed by the softened butter.

Set ganache aside and allow to cool at room temperature while you prepare to assemble your sandwich cookies.

Assembly:

Gently peel cooled lace cookies from the baking parchment.

On a clean sheet of parchment, pair each cookie with another of similar size (not unlike finding mates for your macarons!) Flip one of each pair so that the bottom side of the cookie is facing up.

When ready to use, use a metal whisk to whisk your ganache to piping consistency. (It might take a bit of whisking to reach the desired thickness, but don’t worry–it will firm up eventually!) You want a ganache that is still fairly fluid, so that it flows easily from a piping bag, and will spread evenly when sandwiched between two cookies.

Transfer to a disposable piping bag. Pipe a generous dollop of chocolate ganache into the middle of each cookie. Top with the second cookie and press down gently, allowing ganache to spread to the edges.

Store sandwich cookies in an airtight container at room temperature for up to three days. These cookies also freeze well.